GNU Fortran User Manual

Contributing

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GNU General Public License

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171

GNU Free Documentation License

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183

Funding Free Software

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191

Option Index

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193

Keyword Index

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195

i

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.1

About GNU Fortran . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.2

GNU Fortran and GCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.3

Preprocessing and conditional compilation . . . . . . . . . . . . . . . . . . . . . .

1.4

GNU Fortran and G77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.5

Project Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.6

Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Part I: Invoking GNU Fortran . . . . . . . . . . . . . . . . . . . .

2 GNU Fortran Command Options . . . . . . . . . . . . .

2.1

Option summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.2

Options controlling Fortran dialect . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.3

Options to request or suppress errors and warnings . . . . . . . . . . . .

2.4

Options for debugging your program or GNU Fortran . . . . . . . . . .

2.5

Options for directory search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.6

Influencing the linking step . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.7

Influencing runtime behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.8

Options for code generation conventions . . . . . . . . . . . . . . . . . . . . . . .

2.9

Environment variables affecting gfortran . . . . . . . . . . . . . . . . . . . . .

3 Runtime: Influencing runtime behavior with environment variables . . . . . . . . . . . . . . . . . . . . . . . .

3.1

GFORTRAN_STDIN_UNIT—Unit number for standard input . . . . . .

3.2

GFORTRAN_STDOUT_UNIT—Unit number for standard output . . . .

3.3

GFORTRAN_STDERR_UNIT—Unit number for standard error . . . . . .

3.4

GFORTRAN_USE_STDERR—Send library output to standard error

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3.5

GFORTRAN_TMPDIR—Directory for scratch files . . . . . . . . . . . . . . . . . .

3.6

GFORTRAN_UNBUFFERED_ALL—Don’t buffer I/O on all units . . . . .

3.7

GFORTRAN_UNBUFFERED_PRECONNECTED—Don’t buffer I/O on preconnected units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.8

GFORTRAN_SHOW_LOCUS—Show location for runtime errors . . . . . .

3.9

GFORTRAN_OPTIONAL_PLUS—Print leading + where permitted . .

3.10

GFORTRAN_DEFAULT_RECL—Default record length for new files

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3.11

GFORTRAN_LIST_SEPARATOR—Separator for list output . . . . . . . .

3.12

GFORTRAN_CONVERT_UNIT—Set endianness for unformatted I/O

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3.13

GFORTRAN_ERROR_DUMPCORE—Dump core on run-time errors . .

3.14

GFORTRAN_ERROR_BACKTRACE—Show backtrace on run-time errors

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iii

iv The GNU Fortran Compiler

Part II: Language Reference . . . . . . . . . . . . . . . . . . . . .

4 Fortran 2003 Status . . . . . . . . . . . . . . . . . . . . . . . . . . .

5 Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1

Extensions implemented in GNU Fortran . . . . . . . . . . . . . . . . . . . . . .

5.1.1

Old-style kind specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1.2

Old-style variable initialization . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1.3

Extensions to namelist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1.4

X format descriptor without count field . . . . . . . . . . . . . . . . . . .

5.1.5

Commas in FORMAT specifications . . . . . . . . . . . . . . . . . . . . . . . . .

5.1.6

Missing period in FORMAT specifications . . . . . . . . . . . . . . . . . . .

5.1.7

I/O item lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1.8

BOZ literal constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1.9

Real array indices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1.10

Unary operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1.11

Implicitly convert LOGICAL and INTEGER values . . . . . . . . . .

5.1.12

Hollerith constants support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1.13

Cray pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1.14

CONVERT specifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1.15

OpenMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1.16

Argument list functions %VAL, %REF and %LOC . . . . . . . . . . . .

5.2

Extensions not implemented in GNU Fortran . . . . . . . . . . . . . . . . . .

5.2.1

STRUCTURE and RECORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.2.2

ENCODE and DECODE statements . . . . . . . . . . . . . . . . . . . . . . . . . . .

6 Intrinsic Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.1

Introduction to intrinsic procedures . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.2

ABORT — Abort the program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.3

ABS — Absolute value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.4

ACCESS — Checks file access modes . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.5

ACHAR — Character in

ASCII collating sequence . . . . . . . . . . . . . . . .

6.6

ACOS — Arccosine function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.7

ACOSH — Hyperbolic arccosine function . . . . . . . . . . . . . . . . . . . . . . . .

6.8

ADJUSTL — Left adjust a string . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.9

ADJUSTR — Right adjust a string . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.10

AIMAG — Imaginary part of complex number . . . . . . . . . . . . . . . . .

6.11

AINT — Truncate to a whole number . . . . . . . . . . . . . . . . . . . . . . . . .

6.12

ALARM — Execute a routine after a given delay . . . . . . . . . . . . . . .

6.13

ALL — All values in MASK along DIM are true . . . . . . . . . . . . . .

6.14

ALLOCATED — Status of an allocatable entity . . . . . . . . . . . . . . . . .

6.15

AND — Bitwise logical AND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.16

ANINT — Nearest whole number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.17

ANY — Any value in MASK along DIM is true . . . . . . . . . . . . . . .

6.18

ASIN — Arcsine function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.19

ASINH — Hyperbolic arcsine function . . . . . . . . . . . . . . . . . . . . . . . . .

6.20

ASSOCIATED — Status of a pointer or pointer/target pair . . . . .

6.21

ATAN — Arctangent function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.22

ATAN2 — Arctangent function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.23

ATANH — Hyperbolic arctangent function . . . . . . . . . . . . . . . . . . . . .

6.24

BESJ0 — Bessel function of the first kind of order 0 . . . . . . . . . .

6.25

BESJ1 — Bessel function of the first kind of order 1 . . . . . . . . . .

6.26

BESJN — Bessel function of the first kind . . . . . . . . . . . . . . . . . . . . .

6.27

BESY0 — Bessel function of the second kind of order 0 . . . . . . . .

6.28

BESY1 — Bessel function of the second kind of order 1 . . . . . . . .

6.29

BESYN — Bessel function of the second kind . . . . . . . . . . . . . . . . . .

6.30

BIT_SIZE — Bit size inquiry function . . . . . . . . . . . . . . . . . . . . . . . .

6.31

BTEST — Bit test function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.32

C_ASSOCIATED — Status of a C pointer . . . . . . . . . . . . . . . . . . . . . . .

6.33

C_FUNLOC — Obtain the C address of a procedure . . . . . . . . . . . .

6.34

C_F_PROCPOINTER — Convert C into Fortran procedure pointer

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6.35

C_F_POINTER — Convert C into Fortran pointer . . . . . . . . . . . . . .

6.36

C_LOC — Obtain the C address of an object . . . . . . . . . . . . . . . . . .

6.37

CEILING — Integer ceiling function . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.38

CHAR — Character conversion function . . . . . . . . . . . . . . . . . . . . . . .

6.39

CHDIR — Change working directory . . . . . . . . . . . . . . . . . . . . . . . . . .

6.40

CHMOD — Change access permissions of files . . . . . . . . . . . . . . . . . . .

6.41

CMPLX — Complex conversion function . . . . . . . . . . . . . . . . . . . . . . .

6.42

COMMAND_ARGUMENT_COUNT — Get number of command line arguments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.43

COMPLEX — Complex conversion function . . . . . . . . . . . . . . . . . . . . .

6.44

CONJG — Complex conjugate function . . . . . . . . . . . . . . . . . . . . . . . .

6.45

COS — Cosine function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.46

COSH — Hyperbolic cosine function . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.47

COUNT — Count function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.48

CPU_TIME — CPU elapsed time in seconds . . . . . . . . . . . . . . . . . . . .

6.49

CSHIFT — Circular shift elements of an array . . . . . . . . . . . . . . . . .

6.50

CTIME — Convert a time into a string . . . . . . . . . . . . . . . . . . . . . . . .

6.51

DATE_AND_TIME — Date and time subroutine . . . . . . . . . . . . . . . . .

6.52

DBLE — Double conversion function . . . . . . . . . . . . . . . . . . . . . . . . . .

6.53

DCMPLX — Double complex conversion function . . . . . . . . . . . . . . .

6.54

DFLOAT — Double conversion function . . . . . . . . . . . . . . . . . . . . . . . .

6.55

DIGITS — Significant digits function . . . . . . . . . . . . . . . . . . . . . . . . .

6.56

DIM — Positive difference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.57

DOT_PRODUCT — Dot product function . . . . . . . . . . . . . . . . . . . . . . . .

6.58

DPROD — Double product function . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.59

DREAL — Double real part function . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.60

DTIME — Execution time subroutine (or function) . . . . . . . . . . . .

6.61

EOSHIFT — End-off shift elements of an array . . . . . . . . . . . . . . . .

6.62

EPSILON — Epsilon function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.63

ERF — Error function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.64

ERFC — Error function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.65

ETIME — Execution time subroutine (or function) . . . . . . . . . . . .

6.66

EXIT — Exit the program with status. . . . . . . . . . . . . . . . . . . . . . . .

vi The GNU Fortran Compiler

6.67

EXP — Exponential function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.68

EXPONENT — Exponent function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.69

FDATE — Get the current time as a string . . . . . . . . . . . . . . . . . . . .

6.70

FLOAT — Convert integer to default real . . . . . . . . . . . . . . . . . . . . . .

6.71

FGET — Read a single character in stream mode from stdin . . .

6.72

FGETC — Read a single character in stream mode . . . . . . . . . . . . .

6.73

FLOOR — Integer floor function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.74

FLUSH — Flush I/O unit(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.75

FNUM — File number function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.76

FPUT — Write a single character in stream mode to stdout . . . .

6.77

FPUTC — Write a single character in stream mode . . . . . . . . . . . .

6.78

FRACTION — Fractional part of the model representation . . . . . .

6.79

FREE — Frees memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.80

FSEEK — Low level file positioning subroutine . . . . . . . . . . . . . . . .

6.81

FSTAT — Get file status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.82

FTELL — Current stream position . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.83

GAMMA — Gamma function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.84

GERROR — Get last system error message . . . . . . . . . . . . . . . . . . . . .

6.85

GETARG — Get command line arguments . . . . . . . . . . . . . . . . . . . . .

6.86

GET_COMMAND — Get the entire command line . . . . . . . . . . . . . . . .

6.87

GET_COMMAND_ARGUMENT — Get command line arguments . . . . .

6.88

GETCWD — Get current working directory . . . . . . . . . . . . . . . . . . . . .

6.89

GETENV — Get an environmental variable . . . . . . . . . . . . . . . . . . . . .

6.90

GET_ENVIRONMENT_VARIABLE — Get an environmental variable

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6.91

GETGID — Group ID function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.92

GETLOG — Get login name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.93

GETPID — Process ID function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.94

GETUID — User ID function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.95

GMTIME — Convert time to GMT info . . . . . . . . . . . . . . . . . . . . . . . .

6.96

HOSTNM — Get system host name . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.97

HUGE — Largest number of a kind . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.98

IACHAR — Code in ASCII collating sequence . . . . . . . . . . . . . . . . . .

6.99

IAND — Bitwise logical and . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.100

IARGC — Get the number of command line arguments . . . . . . .

6.101

IBCLR — Clear bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.102

IBITS — Bit extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.103

IBSET — Set bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.104

ICHAR — Character-to-integer conversion function . . . . . . . . . . .

6.105

IDATE — Get current local time subroutine (day/month/year)

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6.106

IEOR — Bitwise logical exclusive or . . . . . . . . . . . . . . . . . . . . . . . . .

6.107

IERRNO — Get the last system error number. . . . . . . . . . . . . . . . .

6.108

INDEX — Position of a substring within a string . . . . . . . . . . . .

6.109

INT — Convert to integer type . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.110

INT2 — Convert to 16-bit integer type . . . . . . . . . . . . . . . . . . . . .

6.111

INT8 — Convert to 64-bit integer type . . . . . . . . . . . . . . . . . . . . .

6.112

IOR — Bitwise logical or . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.113

IRAND — Integer pseudo-random number . . . . . . . . . . . . . . . . . . .

6.114

IS_IOSTAT_END — Test for end-of-file value . . . . . . . . . . . . . . . .

6.115

IS_IOSTAT_EOR — Test for end-of-record value . . . . . . . . . . . . .

6.116

ISATTY — Whether a unit is a terminal device. . . . . . . . . . . . . .

6.117

ISHFT — Shift bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.118

ISHFTC — Shift bits circularly . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.119

ISNAN — Test for a NaN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.120

ITIME — Get current local time subroutine

(hour/minutes/seconds) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.121

KILL — Send a signal to a process . . . . . . . . . . . . . . . . . . . . . . . . .

6.122

KIND — Kind of an entity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.123

LBOUND — Lower dimension bounds of an array . . . . . . . . . . . .

6.124

LEN — Length of a character entity . . . . . . . . . . . . . . . . . . . . . . . .

6.125

LEN_TRIM — Length of a character entity without trailing blank characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.126

LGAMMA — Logarithm of the Gamma function . . . . . . . . . . . . . .

6.127

LGE — Lexical greater than or equal . . . . . . . . . . . . . . . . . . . . . . .

109

6.128

LGT — Lexical greater than . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.129

LINK — Create a hard link . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.130

LLE — Lexical less than or equal . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.131

LLT — Lexical less than . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.132

LNBLNK — Index of the last non-blank character in a string . .

6.133

LOC — Returns the address of a variable . . . . . . . . . . . . . . . . . . .

6.134

LOG — Logarithm function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.135

LOG10 — Base 10 logarithm function . . . . . . . . . . . . . . . . . . . . . . .

6.136

LOGICAL — Convert to logical type . . . . . . . . . . . . . . . . . . . . . . . . .

6.137

LONG — Convert to integer type . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.138

LSHIFT — Left shift bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.139

LSTAT — Get file status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.140

LTIME — Convert time to local time info . . . . . . . . . . . . . . . . . . .

6.141

MALLOC — Allocate dynamic memory . . . . . . . . . . . . . . . . . . . . . .

6.142

MATMUL — matrix multiplication . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.143

MAX — Maximum value of an argument list . . . . . . . . . . . . . . . . .

6.144

MAXEXPONENT — Maximum exponent of a real kind . . . . . . . . .

6.145

MAXLOC — Location of the maximum value within an array . .

6.146

MAXVAL — Maximum value of an array . . . . . . . . . . . . . . . . . . . . .

6.147

MCLOCK — Time function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.148

MCLOCK8 — Time function (64-bit) . . . . . . . . . . . . . . . . . . . . . . . . .

6.149

MERGE — Merge variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.150

MIN — Minimum value of an argument list . . . . . . . . . . . . . . . . .

6.151

MINEXPONENT — Minimum exponent of a real kind . . . . . . . . .

6.152

MINLOC — Location of the minimum value within an array . .

6.153

MINVAL — Minimum value of an array . . . . . . . . . . . . . . . . . . . . .

6.154

MOD — Remainder function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.155

MODULO — Modulo function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.156

MOVE_ALLOC — Move allocation from one object to another

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.157

MVBITS — Move bits from one integer to another . . . . . . . . . . .

vii

viii The GNU Fortran Compiler

6.158

NEAREST — Nearest representable number . . . . . . . . . . . . . . . . . .

6.159

NEW_LINE — New line character . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.160

NINT — Nearest whole number . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.161

NOT — Logical negation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.162

NULL — Function that returns an disassociated pointer . . . . .

6.163

OR — Bitwise logical OR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.164

PACK — Pack an array into an array of rank one . . . . . . . . . . . .

6.165

PERROR — Print system error message . . . . . . . . . . . . . . . . . . . . . .

6.166

PRECISION — Decimal precision of a real kind . . . . . . . . . . . . . .

6.167

PRESENT — Determine whether an optional dummy argument is specified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.168

PRODUCT — Product of array elements . . . . . . . . . . . . . . . . . . . . . .

6.169

RADIX — Base of a model number . . . . . . . . . . . . . . . . . . . . . . . . . .

6.170

RAN — Real pseudo-random number . . . . . . . . . . . . . . . . . . . . . . . .

6.171

RAND — Real pseudo-random number . . . . . . . . . . . . . . . . . . . . . .

6.172

RANDOM_NUMBER — Pseudo-random number . . . . . . . . . . . . . . . . .

6.173

RANDOM_SEED — Initialize a pseudo-random number sequence

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.174

RANGE — Decimal exponent range of a real kind . . . . . . . . . . . .

6.175

REAL — Convert to real type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.176

RENAME — Rename a file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

136

6.177

REPEAT — Repeated string concatenation . . . . . . . . . . . . . . . . . .

6.178

RESHAPE — Function to reshape an array . . . . . . . . . . . . . . . . . . .

6.179

RRSPACING — Reciprocal of the relative spacing . . . . . . . . . . . .

6.180

RSHIFT — Right shift bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.181

SCALE — Scale a real value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.182

SCAN — Scan a string for the presence of a set of characters

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

139

6.183

SECNDS — Time function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.184

SECOND — CPU time function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.185

SELECTED_INT_KIND — Choose integer kind . . . . . . . . . . . . . . . .

6.186

SELECTED_REAL_KIND — Choose real kind . . . . . . . . . . . . . . . . . .

6.187

SET_EXPONENT — Set the exponent of the model . . . . . . . . . . .

6.188

SHAPE — Determine the shape of an array . . . . . . . . . . . . . . . . . .

6.189

SIGN — Sign copying function . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.190

SIGNAL — Signal handling subroutine (or function) . . . . . . . . .

6.191

SIN — Sine function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.192

SINH — Hyperbolic sine function . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.193

SIZE — Determine the size of an array . . . . . . . . . . . . . . . . . . . . .

6.194

SIZEOF — Size in bytes of an expression . . . . . . . . . . . . . . . . . . .

6.195

SLEEP — Sleep for the specified number of seconds . . . . . . . . .

6.196

SNGL — Convert double precision real to default real . . . . . . .

6.197

SPACING — Smallest distance between two numbers of a given type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.198

SPREAD — Add a dimension to an array . . . . . . . . . . . . . . . . . . . .

6.199

SQRT — Square-root function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.200

SRAND — Reinitialize the random number generator . . . . . . . .

6.201

STAT — Get file status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.202

SUM — Sum of array elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.203

SYMLNK — Create a symbolic link . . . . . . . . . . . . . . . . . . . . . . . . . .

6.204

SYSTEM — Execute a shell command . . . . . . . . . . . . . . . . . . . . . . .

6.205

SYSTEM_CLOCK — Time function . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.206

TAN — Tangent function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.207

TANH — Hyperbolic tangent function . . . . . . . . . . . . . . . . . . . . . . .

6.208

TIME — Time function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

154

6.209

TIME8 — Time function (64-bit) . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.210

TINY — Smallest positive number of a real kind . . . . . . . . . . . .

6.211

TRANSFER — Transfer bit patterns . . . . . . . . . . . . . . . . . . . . . . . . .

6.212

TRANSPOSE — Transpose an array of rank two . . . . . . . . . . . . . .

6.213

TRIM — Remove trailing blank characters of a string . . . . . . .

6.214

TTYNAM — Get the name of a terminal device. . . . . . . . . . . . . . .

6.215

UBOUND — Upper dimension bounds of an array . . . . . . . . . . . .

6.216

UMASK — Set the file creation mask . . . . . . . . . . . . . . . . . . . . . . . .

6.217

UNLINK — Remove a file from the file system . . . . . . . . . . . . . . .

6.218

UNPACK — Unpack an array of rank one into an array . . . . . .

6.219

VERIFY — Scan a string for the absence of a set of characters

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.220

XOR — Bitwise logical exclusive OR . . . . . . . . . . . . . . . . . . . . . . . .

7 Intrinsic Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7.1

ISO_FORTRAN_ENV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7.2

ISO_C_BINDING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7.3

OpenMP Modules OMP_LIB and OMP_LIB_KINDS . . . . . . . . . . . . . .

165

Contributing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contributors to GNU Fortran . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section 2.2 [Options controlling Fortran dialect], page 8 .

Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

168

Proposed Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

168

Compiler extensions: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

168

Environment Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

169

GNU General Public License . . . . . . . . . . . . . . . . . . .

171

GNU Free Documentation License . . . . . . . . . . . . .

183

ADDENDUM: How to use this License for your documents . . . . . . . .

189

Funding Free Software . . . . . . . . . . . . . . . . . . . . . . . . . . .

191

Option Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

193

Keyword Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

195

Chapter 1: Introduction

1 Introduction

This manual documents the use of gfortran, the GNU Fortran compiler. You can find in this manual how to invoke gfortran, as well as its features and incompatibilities.

The GNU Fortran compiler front end was designed initially as a free replacement for, or alternative to, the unix f95 command; gfortran is the command you’ll use to invoke the compiler.

1.1 About GNU Fortran

The GNU Fortran compiler is still in an early state of development. It can generate code for most constructs and expressions, but much work remains to be done.

When the GNU Fortran compiler is finished, it will do everything you expect from any decent compiler:

• Read a user’s program, stored in a file and containing instructions written in Fortran

77, Fortran 90, Fortran 95 or Fortran 2003. This file contains source code.

• Translate the user’s program into instructions a computer can carry out more quickly than it takes to translate the instructions in the first place. The result after compilation of a program is machine code, code designed to be efficiently translated and processed by a machine such as your computer. Humans usually aren’t as good writing machine code as they are at writing Fortran (or C++, Ada, or Java), because is easy to make tiny mistakes writing machine code.

• Provide the user with information about the reasons why the compiler is unable to create a binary from the source code. Usually this will be the case if the source code is flawed. When writing Fortran, it is easy to make big mistakes. The Fortran 90 requires that the compiler can point out mistakes to the user. An incorrect usage of the language causes an error message.

The compiler will also attempt to diagnose cases where the user’s program contains a correct usage of the language, but instructs the computer to do something questionable.

This kind of diagnostics message is called a warning message.

• Provide optional information about the translation passes from the source code to machine code. This can help a user of the compiler to find the cause of certain bugs which may not be obvious in the source code, but may be more easily found at a lower level compiler output. It also helps developers to find bugs in the compiler itself.

• Provide information in the generated machine code that can make it easier to find bugs in the program (using a debugging tool, called a debugger, such as the GNU Debugger gdb).

• Locate and gather machine code already generated to perform actions requested by statements in the user’s program. This machine code is organized into modules and is located and linked to the user program.

The GNU Fortran compiler consists of several components:

• A version of the gcc command (which also might be installed as the system’s cc command) that also understands and accepts Fortran source code. The gcc command is the driver program for all the languages in the GNU Compiler Collection (GCC); With

2 The GNU Fortran Compiler gcc, you can compile the source code of any language for which a front end is available in GCC.

• The gfortran command itself, which also might be installed as the system’s f95 command. gfortran is just another driver program, but specifically for the Fortran compiler only. The difference with gcc is that gfortran will automatically link the correct libraries to your program.

• A collection of run-time libraries. These libraries contain the machine code needed to support capabilities of the Fortran language that are not directly provided by the machine code generated by the gfortran compilation phase, such as intrinsic functions and subroutines, and routines for interaction with files and the operating system.

• The Fortran compiler itself, (f951). This is the GNU Fortran parser and code generator, linked to and interfaced with the GCC backend library. f951 “translates” the source code to assembler code. You would typically not use this program directly; instead, the gcc or gfortran driver programs will call it for you.

1.2 GNU Fortran and GCC

GNU Fortran is a part of GCC, the GNU Compiler Collection. GCC consists of a collection of front ends for various languages, which translate the source code into a languageindependent form called GENERIC. This is then processed by a common middle end which provides optimization, and then passed to one of a collection of back ends which generate code for different computer architectures and operating systems.

Functionally, this is implemented with a driver program (gcc) which provides the command-line interface for the compiler. It calls the relevant compiler front-end program

(e.g., f951 for Fortran) for each file in the source code, and then calls the assembler and linker as appropriate to produce the compiled output. In a copy of GCC which has been compiled with Fortran language support enabled, gcc will recognize files with ‘.f’,

‘.for’, ‘.ftn’, ‘.f90’, ‘.f95’, and ‘.f03’ extensions as Fortran source code, and compile it accordingly. A gfortran driver program is also provided, which is identical to gcc except that it automatically links the Fortran runtime libraries into the compiled program.

Source files with ‘.f’, ‘.for’, ‘.fpp’, ‘.ftn’, ‘.F’, ‘.FOR’, ‘.FPP’, and ‘.FTN’ extensions are treated as fixed form.

Source files with ‘.f90’, ‘.f95’, ‘.f03’, ‘.F90’, ‘.F95’, and

‘.F03’ extensions are treated as free form. The capitalized versions of either form are run through preprocessing. Source files with the lower case ‘.fpp’ extension are also run through preprocessing.

This manual specifically documents the Fortran front end, which handles the programming language’s syntax and semantics. The aspects of GCC which relate to the optimization passes and the back-end code generation are documented in the GCC manual; see Section

“Introduction” in Using the GNU Compiler Collection (GCC) . The two manuals together provide a complete reference for the GNU Fortran compiler.

1.3 Preprocessing and conditional compilation

Many Fortran compilers including GNU Fortran allow passing the source code through a

C preprocessor (CPP; sometimes also called the Fortran preprocessor, FPP) to allow for conditional compilation. In the case of GNU Fortran, this is the GNU C Preprocessor

Chapter 1: Introduction 3 in the traditional mode. On systems with case-preserving file names, the preprocessor is automatically invoked if the file extension is .F, .FOR, .FTN, .F90, .F95 or .F03; otherwise use for fixed-format code the option -x f77-cpp-input and for free-format code -x f95cpp-input. Invocation of the preprocessor can be suppressed using -x f77 or -x f95.

If the GNU Fortran invoked the preprocessor, __GFORTRAN__ is defined and __GNUC__,

__GNUC_MINOR__ and __GNUC_PATCHLEVEL__ can be used to determine the version of the compiler. See Section “Overview” in The C Preprocessor for details.

While CPP is the de-facto standard for preprocessing Fortran code, Part 3 of the Fortran

95 standard (ISO/IEC 1539-3:1998) defines Conditional Compilation, which is not widely used and not directly supported by the GNU Fortran compiler. You can use the program coco to preprocess such files ( http://users.erols.com/dnagle/coco.html

1.4 GNU Fortran and G77

The GNU Fortran compiler is the successor to g77, the Fortran 77 front end included in GCC prior to version 4. It is an entirely new program that has been designed to provide Fortran

95 support and extensibility for future Fortran language standards, as well as providing backwards compatibility for Fortran 77 and nearly all of the GNU language extensions supported by g77.

1.5 Project Status

As soon as gfortran can parse all of the statements correctly, it will be in the

“larva” state. When we generate code, the “puppa” state. When gfortran is done, we’ll see if it will be a beautiful butterfly, or just a big bug....

–Andy Vaught, April 2000

The start of the GNU Fortran 95 project was announced on the GCC homepage in March

18, 2000 (even though Andy had already been working on it for a while, of course).

The GNU Fortran compiler is able to compile nearly all standard-compliant Fortran 95,

Fortran 90, and Fortran 77 programs, including a number of standard and non-standard extensions, and can be used on real-world programs. In particular, the supported extensions include OpenMP, Cray-style pointers, and several Fortran 2003 features such as enumeration, stream I/O, and some of the enhancements to allocatable array support from TR

15581. However, it is still under development and has a few remaining rough edges.

At present, the GNU Fortran compiler passes the NIST Fortran 77 Test Suite , and produces acceptable results on the LAPACK Test Suite . It also provides respectable performance on the Polyhedron Fortran compiler benchmarks and the Livermore Fortran Kernels test . It has been used to compile a number of large real-world programs, including the HIRLAM weather-forecasting code and the Tonto quantum chemistry package ; see http://gcc.gnu.org/wiki/GfortranApps for an extended list.

Among other things, the GNU Fortran compiler is intended as a replacement for G77.

At this point, nearly all programs that could be compiled with G77 can be compiled with

GNU Fortran, although there are a few minor known regressions.

The primary work remaining to be done on GNU Fortran falls into three categories: bug fixing (primarily regarding the treatment of invalid code and providing useful error

4 The GNU Fortran Compiler messages), improving the compiler optimizations and the performance of compiled code, and extending the compiler to support future standards—in particular, Fortran 2003.

1.6 Standards

The GNU Fortran compiler implements ISO/IEC 1539:1997 (Fortran 95). As such, it can also compile essentially all standard-compliant Fortran 90 and Fortran 77 programs. It also supports the ISO/IEC TR-15581 enhancements to allocatable arrays, and the OpenMP

Application Program Interface v2.5

specification.

In the future, the GNU Fortran compiler may also support other standard variants of and extensions to the Fortran language. These include ISO/IEC 1539-1:2004 (Fortran 2003).

Chapter 1: Introduction

Part I: Invoking GNU Fortran

Chapter 2: GNU Fortran Command Options

2 GNU Fortran Command Options

The gfortran command supports all the options supported by the gcc command. Only options specific to GNU Fortran are documented here.

See Section “GCC Command Options” in Using the GNU Compiler Collection (GCC) , for information on the non-Fortran-specific aspects of the gcc command (and, therefore, the gfortran command).

All GCC and GNU Fortran options are accepted both by gfortran and by gcc (as well as any other drivers built at the same time, such as g++), since adding GNU Fortran to the

GCC distribution enables acceptance of GNU Fortran options by all of the relevant drivers.

In some cases, options have positive and negative forms; the negative form of ‘-ffoo’ would be ‘-fno-foo’. This manual documents only one of these two forms, whichever one is not the default.

2.1 Option summary

Here is a summary of all the options specific to GNU Fortran, grouped by type. Explanations are in the following sections.

Fortran Language Options

See

-fall-intrinsics -ffree-form -fno-fixed-form

-fdollar-ok -fimplicit-none -fmax-identifier-length

-std=std -fd-lines-as-code -fd-lines-as-comments

-ffixed-line-length-n -ffixed-line-length-none

-ffree-line-length-n -ffree-line-length-none

-fdefault-double-8 -fdefault-integer-8 -fdefault-real-8

-fcray-pointer -fopenmp -fno-range-check -fbackslash -fmodule-private

Error and Warning Options

See

Section 2.3 [Options to request or suppress errors and warnings], page 10

-fmax-errors=n

-fsyntax-only -pedantic -pedantic-errors

-Wall -Waliasing -Wampersand -Wcharacter-truncation -Wconversion

-Wimplicit-interface -Wline-truncation -Wnonstd-intrinsics -Wsurprising

-Wno-tabs -Wunderflow -Wunused-parameter

Debugging Options

See

Section 2.4 [Options for debugging your program or GNU Fortran], page 12

-fdump-parse-tree -ffpe-trap=list

-fdump-core -fbacktrace

Directory Options

See

Section 2.5 [Options for directory search], page 13 .

-Idir -Jdir -Mdir -fintrinsic-modules-path dir

Link Options

See

Section 2.6 [Options for influencing the linking step], page 13 .

-static-libgfortran

Runtime Options

See

Section 2.7 [Options for influencing runtime behavior], page 14

8 The GNU Fortran Compiler

-fconvert=conversion -frecord-marker=length

-fmax-subrecord-length=length -fsign-zero

Code Generation Options

See

Section 2.8 [Options for code generation conventions], page 14

-fno-automatic -ff2c -fno-underscoring -fsecond-underscore

-fbounds-check -fmax-stack-var-size=n

-fpack-derived -frepack-arrays -fshort-enums -fexternal-blas

-fblas-matmul-limit=n -frecursive -finit-local-zero

-finit-integer=n -finit-real=<zero|inf|-inf|nan>

-finit-logical=<true|false> -finit-character=n

2.2 Options controlling Fortran dialect

The following options control the details of the Fortran dialect accepted by the compiler:

-ffree-form

-ffixed-form

Specify the layout used by the source file. The free form layout was introduced in Fortran 90. Fixed form was traditionally used in older Fortran programs.

When neither option is specified, the source form is determined by the file extension.

-fall-intrinsics

Accept all of the intrinsic procedures provided in libgfortran without regard to the setting of ‘-std’. In particular, this option can be quite useful with

‘-std=f95’. Additionally, gfortran will ignore ‘-Wnonstd-intrinsics’.

-fd-lines-as-code

-fd-lines-as-comments

Enable special treatment for lines beginning with d or D in fixed form sources. If the ‘-fd-lines-as-code’ option is given they are treated as if the first column contained a blank. If the ‘-fd-lines-as-comments’ option is given, they are treated as comment lines.

-fdefault-double-8

Set the DOUBLE PRECISION type to an 8 byte wide type.

-fdefault-integer-8

Set the default integer and logical types to an 8 byte wide type. Do nothing if this is already the default.

-fdefault-real-8

Set the default real type to an 8 byte wide type. Do nothing if this is already the default.

-fdollar-ok

Allow ‘$’ as a valid character in a symbol name.

-fbackslash

Change the interpretation of backslashes in string literals from a single backslash character to “C-style” escape characters.

The following combinations are expanded \a, \b, \f, \n, \r, \t, \v, \\, and \0 to the ASCII characters alert, backspace, form feed, newline, carriage return, horizontal tab, vertical

Chapter 2: GNU Fortran Command Options 9 tab, backslash, and NUL, respectively. All other combinations of a character preceded by \ are unexpanded.

-fmodule-private

Set the default accessibility of module entities to PRIVATE. Use-associated entities will not be accessible unless they are explicitly declared as PUBLIC.

-ffixed-line-length-n

Set column after which characters are ignored in typical fixed-form lines in the source file, and through which spaces are assumed (as if padded to that length) after the ends of short fixed-form lines.

Popular values for n include 72 (the standard and the default), 80 (card image), and 132 (corresponding to “extended-source” options in some popular compilers). n may also be ‘none’, meaning that the entire line is meaningful and that continued character constants never have implicit spaces appended to them to fill out the line. ‘-ffixed-line-length-0’ means the same thing as

‘-ffixed-line-length-none’.

-ffree-line-length-n

Set column after which characters are ignored in typical free-form lines in the source file.

The default value is 132.

n may be ‘none’, meaning that the entire line is meaningful. ‘-ffree-line-length-0’ means the same thing as

‘-ffree-line-length-none’.

-fmax-identifier-length=n

Specify the maximum allowed identifier length. Typical values are 31 (Fortran

95) and 63 (Fortran 2003).

-fimplicit-none

Specify that no implicit typing is allowed, unless overridden by explicit

IMPLICIT statements. This is the equivalent of adding implicit none to the start of every procedure.

-fcray-pointer

Enable the Cray pointer extension, which provides C-like pointer functionality.

-fopenmp

Enable the OpenMP extensions. This includes OpenMP !$omp directives in free form and c$omp, *$omp and !$omp directives in fixed form, !$ conditional compilation sentinels in free form and c$, *$ and !$ sentinels in fixed form, and when linking arranges for the OpenMP runtime library to be linked in. The option ‘-fopenmp’ implies ‘-frecursive’.

-fno-range-check

Disable range checking on results of simplification of constant expressions during compilation. For example, GNU Fortran will give an error at compile time when simplifying a = 1. / 0. With this option, no error will be given and a will be assigned the value +Infinity. If an expression evaluates to a value outside of the relevant range of [-HUGE():HUGE()], then the expression will be replaced by

-Inf or +Inf as appropriate. Similarly, DATA i/Z’FFFFFFFF’/ will result in an integer overflow on most systems, but with ‘-fno-range-check’ the value will

“wrap around” and i will be initialized to −1 instead.

10 The GNU Fortran Compiler

-std=std

Specify the standard to which the program is expected to conform, which may be one of ‘f95’, ‘f2003’, ‘gnu’, or ‘legacy’. The default value for std is ‘gnu’, which specifies a superset of the Fortran 95 standard that includes all of the extensions supported by GNU Fortran, although warnings will be given for obsolete extensions not recommended for use in new code. The ‘legacy’ value is equivalent but without the warnings for obsolete extensions, and may be useful for old non-standard programs. The ‘f95’ and ‘f2003’ values specify strict conformance to the Fortran 95 and Fortran 2003 standards, respectively; errors are given for all extensions beyond the relevant language standard, and warnings are given for the Fortran 77 features that are permitted but obsolescent in later standards.

2.3 Options to request or suppress errors and warnings

Errors are diagnostic messages that report that the GNU Fortran compiler cannot compile the relevant piece of source code. The compiler will continue to process the program in an attempt to report further errors to aid in debugging, but will not produce any compiled output.

Warnings are diagnostic messages that report constructions which are not inherently erroneous but which are risky or suggest there is likely to be a bug in the program. Unless

‘-Werror’ is specified, they do not prevent compilation of the program.

You can request many specific warnings with options beginning ‘-W’, for example

‘-Wimplicit’ to request warnings on implicit declarations. Each of these specific warning options also has a negative form beginning ‘-Wno-’ to turn off warnings; for example,

‘-Wno-implicit’.

This manual lists only one of the two forms, whichever is not the default.

These options control the amount and kinds of errors and warnings produced by GNU

Fortran:

-fmax-errors=n

Limits the maximum number of error messages to n, at which point GNU

Fortran bails out rather than attempting to continue processing the source code. If n is 0, there is no limit on the number of error messages produced.

-fsyntax-only

Check the code for syntax errors, but don’t actually compile it.

This will generate module files for each module present in the code, but no other output file.

-pedantic

Issue warnings for uses of extensions to Fortran 95. ‘-pedantic’ also applies to

C-language constructs where they occur in GNU Fortran source files, such as use of ‘\e’ in a character constant within a directive like #include.

Valid Fortran 95 programs should compile properly with or without this option.

However, without this option, certain GNU extensions and traditional Fortran features are supported as well. With this option, many of them are rejected.

Some users try to use ‘-pedantic’ to check programs for conformance. They soon find that it does not do quite what they want—it finds some nonstandard

Chapter 2: GNU Fortran Command Options 11 practices, but not all. However, improvements to GNU Fortran in this area are welcome.

This should be used in conjunction with ‘-std=f95’ or ‘-std=f2003’.

-pedantic-errors

Like ‘-pedantic’, except that errors are produced rather than warnings.

-Wall

Enables commonly used warning options pertaining to usage that we recommend avoiding and that we believe are easy to avoid.

This currently includes ‘-Waliasing’, ‘-Wampersand’, ‘-Wsurprising’, ‘-Wnonstd-intrinsics’,

‘-Wno-tabs’, and ‘-Wline-truncation’.

-Waliasing

Warn about possible aliasing of dummy arguments. Specifically, it warns if the same actual argument is associated with a dummy argument with INTENT(IN) and a dummy argument with INTENT(OUT) in a call with an explicit interface.

The following example will trigger the warning.

interface subroutine bar(a,b) integer, intent(in) :: a integer, intent(out) :: b end subroutine end interface integer :: a call bar(a,a)

-Wampersand

Warn about missing ampersand in continued character constants. The warning is given with ‘-Wampersand’, ‘-pedantic’, ‘-std=f95’, and ‘-std=f2003’. Note:

With no ampersand given in a continued character constant, GNU Fortran assumes continuation at the first non-comment, non-whitespace character after the ampersand that initiated the continuation.

-Wcharacter-truncation

Warn when a character assignment will truncate the assigned string.

-Wconversion

Warn about implicit conversions between different types.

-Wimplicit-interface

Warn if a procedure is called without an explicit interface. Note this only checks that an explicit interface is present. It does not check that the declared interfaces are consistent across program units.

-Wnonstd-intrinsics

Warn if the user tries to use an intrinsic that does not belong to the standard the user has chosen via the ‘-std’ option.

-Wsurprising

Produce a warning when “suspicious” code constructs are encountered. While technically legal these usually indicate that an error has been made.

This currently produces a warning under the following circumstances:

12 The GNU Fortran Compiler

• An INTEGER SELECT construct has a CASE that can never be matched as its lower value is greater than its upper value.

• A LOGICAL SELECT construct has three CASE statements.

• A TRANSFER specifies a source that is shorter than the destination.

-Wtabs

By default, tabs are accepted as whitespace, but tabs are not members of the

Fortran Character Set. For continuation lines, a tab followed by a digit between 1 and 9 is supported. ‘-Wno-tabs’ will cause a warning to be issued if a tab is encountered. Note, ‘-Wno-tabs’ is active for ‘-pedantic’, ‘-std=f95’,

‘-std=f2003’, and ‘-Wall’.

-Wunderflow

Produce a warning when numerical constant expressions are encountered, which yield an UNDERFLOW during compilation.

-Wunused-parameter

Contrary to gcc’s meaning of ‘-Wunused-parameter’, gfortran’s implementation of this option does not warn about unused dummy arguments, but about unused PARAMETER values. ‘-Wunused-parameter’ is not included in ‘-Wall’ but is implied by ‘-Wall -Wextra’.

-Werror

Turns all warnings into errors.

See Section “Options to Request or Suppress Errors and Warnings” in Using the GNU

Compiler Collection (GCC) , for information on more options offered by the GBE shared by gfortran, gcc and other GNU compilers.

Some of these have no effect when compiling programs written in Fortran.

2.4 Options for debugging your program or GNU Fortran

GNU Fortran has various special options that are used for debugging either your program or the GNU Fortran compiler.

-fdump-parse-tree

Output the internal parse tree before starting code generation. Only really useful for debugging the GNU Fortran compiler itself.

-ffpe-trap=list

Specify a list of IEEE exceptions when a Floating Point Exception (FPE) should be raised. On most systems, this will result in a SIGFPE signal being sent and the program being interrupted, producing a core file useful for debugging. list is a (possibly empty) comma-separated list of the following IEEE exceptions:

‘invalid’ (invalid floating point operation, such as SQRT(-1.0)), ‘zero’ (division by zero), ‘overflow’ (overflow in a floating point operation), ‘underflow’

(underflow in a floating point operation), ‘precision’ (loss of precision during operation) and ‘denormal’ (operation produced a denormal value).

Some of the routines in the Fortran runtime library, like ‘CPU_TIME’, are likely to to trigger floating point exceptions when ffpe-trap=precision is used. For this reason, the use of ffpe-trap=precision is not recommended.

Chapter 2: GNU Fortran Command Options 13

-fbacktrace

Specify that, when a runtime error is encountered or a deadly signal is emitted

(segmentation fault, illegal instruction, bus error or floating-point exception), the Fortran runtime library should output a backtrace of the error. This option only has influence for compilation of the Fortran main program.

-fdump-core

Request that a core-dump file is written to disk when a runtime error is encountered on systems that support core dumps. This option is only effective for the compilation of the Fortran main program.

See Section “Options for Debugging Your Program or GCC” in Using the GNU Compiler

Collection (GCC) , for more information on debugging options.

2.5 Options for directory search

These options affect how GNU Fortran searches for files specified by the INCLUDE directive and where it searches for previously compiled modules.

It also affects the search paths used by cpp when used to preprocess Fortran source.

-Idir

These affect interpretation of the INCLUDE directive (as well as of the #include directive of the cpp preprocessor).

Also note that the general behavior of ‘-I’ and INCLUDE is pretty much the same as of ‘-I’ with #include in the cpp preprocessor, with regard to looking for ‘header.gcc’ files and other such things.

This path is also used to search for ‘.mod’ files when previously compiled modules are required by a USE statement.

See Section “Options for Directory Search” in Using the GNU Compiler Collection (GCC) , for information on the ‘-I’ option.

-Mdir

-Jdir

This option specifies where to put ‘.mod’ files for compiled modules. It is also added to the list of directories to searched by an USE statement.

The default is the current directory.

‘-J’ is an alias for ‘-M’ to avoid conflicts with existing GCC options.

-fintrinsic-modules-path dir

This option specifies the location of pre-compiled intrinsic modules, if they are not in the default location expected by the compiler.

2.6 Influencing the linking step

These options come into play when the compiler links object files into an executable output file. They are meaningless if the compiler is not doing a link step.

-static-libgfortran

On systems that provide ‘libgfortran’ as a shared and a static library, this option forces the use of the static version. If no shared version of ‘libgfortran’ was built when the compiler was configured, this option has no effect.

14 The GNU Fortran Compiler

2.7 Influencing runtime behavior

These options affect the runtime behavior of programs compiled with GNU Fortran.

-fconvert=conversion

Specify the representation of data for unformatted files.

Valid values for conversion are: ‘native’, the default; ‘swap’, swap between big- and little-endian; ‘big-endian’, use big-endian representation for unformatted files; ‘little-endian’, use little-endian representation for unformatted files.

This option has an effect only when used in the main program. The CONVERT specifier and the GFORTRAN CONVERT UNIT environment variable override the default specified by ‘-fconvert’.

-frecord-marker=length

Specify the length of record markers for unformatted files. Valid values for length are 4 and 8. Default is 4. This is different from previous versions of gfortran, which specified a default record marker length of 8 on most systems.

If you want to read or write files compatible with earlier versions of gfortran, use ‘-frecord-marker=8’.

-fmax-subrecord-length=length

Specify the maximum length for a subrecord. The maximum permitted value for length is 2147483639, which is also the default. Only really useful for use by the gfortran testsuite.

-fsign-zero

When writing zero values, show the negative sign if the sign bit is set. fnosign-zero does not print the negative sign of zero values for compatibility with

F77. Default behavior is to show the negative sign.

2.8 Options for code generation conventions

These machine-independent options control the interface conventions used in code generation.

Most of them have both positive and negative forms; the negative form of ‘-ffoo’ would be ‘-fno-foo’. In the table below, only one of the forms is listed—the one which is not the default. You can figure out the other form by either removing ‘no-’ or adding it.

-fno-automatic

Treat each program unit (except those marked as RECURSIVE) as if the

SAVE statement were specified for every local variable and array referenced in it.

Does not affect common blocks.

(Some Fortran compilers provide this option under the name ‘-static’ or ‘-save’.) The default, which is

‘-fautomatic’, uses the stack for local variables smaller than the value given by ‘-fmax-stack-var-size’. Use the option ‘-frecursive’ to use no static memory.

-ff2c

Generate code designed to be compatible with code generated by g77 and f2c.

The calling conventions used by g77 (originally implemented in f2c) require functions that return type default REAL to actually return the C type double, and functions that return type COMPLEX to return the values via an extra

Chapter 2: GNU Fortran Command Options 15 argument in the calling sequence that points to where to store the return value. Under the default GNU calling conventions, such functions simply return their results as they would in GNU C—default REAL functions return the C type float, and COMPLEX functions return the GNU C type complex.

Additionally, this option implies the ‘-fsecond-underscore’ option, unless

‘-fno-second-underscore’ is explicitly requested.

This does not affect the generation of code that interfaces with the libgfortran library.

Caution: It is not a good idea to mix Fortran code compiled with ‘-ff2c’ with code compiled with the default ‘-fno-f2c’ calling conventions as, calling

COMPLEX or default REAL functions between program parts which were compiled with different calling conventions will break at execution time.

Caution: This will break code which passes intrinsic functions of type default

REAL or COMPLEX as actual arguments, as the library implementations use the

‘-fno-f2c’ calling conventions.

-fno-underscoring

Do not transform names of entities specified in the Fortran source file by appending underscores to them.

With ‘-funderscoring’ in effect, GNU Fortran appends one underscore to external names with no underscores. This is done to ensure compatibility with code produced by many UNIX Fortran compilers.

Caution: The default behavior of GNU Fortran is incompatible with f2c and g77, please use the ‘-ff2c’ option if you want object files compiled with GNU

Fortran to be compatible with object code created with these tools.

Use of ‘-fno-underscoring’ is not recommended unless you are experimenting with issues such as integration of GNU Fortran into existing system environ-

For example, with ‘-funderscoring’, and assuming other defaults like

‘-fcase-lower’ and that j() and max_count() are external functions while my_var and lvar are local variables, a statement like

I = J() + MAX_COUNT (MY_VAR, LVAR) is implemented as something akin to: i = j_() + max_count__(&my_var__, &lvar);

With ‘-fno-underscoring’, the same statement is implemented as: i = j() + max_count(&my_var, &lvar);

Use of ‘-fno-underscoring’ allows direct specification of user-defined names while debugging and when interfacing GNU Fortran code with other languages.

Note that just because the names match does not mean that the interface implemented by GNU Fortran for an external name matches the interface implemented by some other language for that same name. That is, getting code produced by GNU Fortran to link to code produced by some other compiler using this or any other method can be only a small part of the overall solution— getting the code generated by both compilers to agree on issues other than

16 The GNU Fortran Compiler naming can require significant effort, and, unlike naming disagreements, linkers normally cannot detect disagreements in these other areas.

Also, note that with ‘-fno-underscoring’, the lack of appended underscores introduces the very real possibility that a user-defined external name will conflict with a name in a system library, which could make finding unresolved-reference bugs quite difficult in some cases—they might occur at program run time, and show up only as buggy behavior at run time.

In future versions of GNU Fortran we hope to improve naming and linking issues so that debugging always involves using the names as they appear in the source, even if the names as seen by the linker are mangled to prevent accidental linking between procedures with incompatible interfaces.

-fsecond-underscore

By default, GNU Fortran appends an underscore to external names. If this option is used GNU Fortran appends two underscores to names with underscores and one underscore to external names with no underscores. GNU Fortran also appends two underscores to internal names with underscores to avoid naming collisions with external names.

This option has no effect if ‘-fno-underscoring’ is in effect. It is implied by the ‘-ff2c’ option.

Otherwise, with this option, an external name such as MAX_COUNT is implemented as a reference to the link-time external symbol max_count__, instead of max_count_. This is required for compatibility with g77 and f2c, and is implied by use of the ‘-ff2c’ option.

-fbounds-check

Enable generation of run-time checks for array subscripts and against the declared minimum and maximum values. It also checks array indices for assumed and deferred shape arrays against the actual allocated bounds.

Some checks require that ‘-fbounds-check’ is set for the compilation of the main program.

In the future this may also include other forms of checking, e.g., checking substring references.

-fmax-stack-var-size=n

This option specifies the size in bytes of the largest array that will be put on the stack; if the size is exceeded static memory is used (except in procedures marked as RECURSIVE). Use the option ‘-frecursive’ to allow for recursive procedures which do not have a RECURSIVE attribute or for parallel programs.

Use ‘-fno-automatic’ to never use the stack.

This option currently only affects local arrays declared with constant bounds, and may not apply to all character variables. Future versions of GNU Fortran may improve this behavior.

The default value for n is 32768.

Chapter 2: GNU Fortran Command Options 17

-fpack-derived

This option tells GNU Fortran to pack derived type members as closely as possible. Code compiled with this option is likely to be incompatible with code compiled without this option, and may execute slower.

-frepack-arrays

In some circumstances GNU Fortran may pass assumed shape array sections via a descriptor describing a noncontiguous area of memory. This option adds code to the function prologue to repack the data into a contiguous block at runtime.

This should result in faster accesses to the array. However it can introduce significant overhead to the function call, especially when the passed data is noncontiguous.

-fshort-enums

This option is provided for interoperability with C code that was compiled with the ‘-fshort-enums’ option. It will make GNU Fortran choose the smallest

INTEGER kind a given enumerator set will fit in, and give all its enumerators this kind.

-fexternal-blas

This option will make gfortran generate calls to BLAS functions for some matrix operations like MATMUL, instead of using our own algorithms, if the size of the matrices involved is larger than a given limit (see ‘-fblas-matmul-limit’).

This may be profitable if an optimized vendor BLAS library is available. The

BLAS library will have to be specified at link time.

-fblas-matmul-limit=n

Only significant when ‘-fexternal-blas’ is in effect. Matrix multiplication of matrices with size larger than (or equal to) n will be performed by calls to

BLAS functions, while others will be handled by gfortran internal algorithms.

If the matrices involved are not square, the size comparison is performed using the geometric mean of the dimensions of the argument and result matrices.

The default value for n is 30.

-frecursive

Allow indirect recursion by forcing all local arrays to be allocated on the stack. This flag cannot be used together with ‘-fmax-stack-var-size=’ or

‘-fno-automatic’.

-finit-local-zero

-finit-integer=n

-finit-real=<zero|inf|-inf|nan>

-finit-logical=<true|false>

-finit-character=n

The ‘-finit-local-zero’ option instructs the compiler to initialize local

INTEGER, REAL, and COMPLEX variables to zero, LOGICAL variables to false, and CHARACTER variables to a string of null bytes. Finer-grained initialization options are provided by the ‘-finit-integer=n ’, ‘-finit-real=<zero|inf|inf|nan>’ (which also initializes the real and imaginary parts of local COMPLEX

18 The GNU Fortran Compiler variables), ‘-finit-logical=<true|false>’, and ‘-finit-character=n ’

(where n is an ASCII character value) options. These options do not initialize components of derived type variables, nor do they initialize variables that appear in an EQUIVALENCE statement. (This limitation may be removed in future releases).

Note that the ‘-finit-real=nan’ option initializes REAL and COMPLEX variables with a quiet NaN.

See Section “Options for Code Generation Conventions” in Using the GNU Compiler

Collection (GCC) , for information on more options offered by the GBE shared by gfortran, gcc, and other GNU compilers.

2.9 Environment variables affecting gfortran

The gfortran compiler currently does not make use of any environment variables to control its operation above and beyond those that affect the operation of gcc.

See Section “Environment Variables Affecting GCC” in Using the GNU Compiler Collection (GCC) , for information on environment variables.

See

Chapter 3 [Runtime], page 19

, for environment variables that affect the run-time behavior of programs compiled with GNU Fortran.

Chapter 3: Runtime: Influencing runtime behavior with environment variables 19

3 Runtime: Influencing runtime behavior with environment variables

The behavior of the gfortran can be influenced by environment variables.

Malformed environment variables are silently ignored.

3.1 GFORTRAN_STDIN_UNIT—Unit number for standard input

This environment variable can be used to select the unit number preconnected to standard input. This must be a positive integer. The default value is 5.

3.2 GFORTRAN_STDOUT_UNIT—Unit number for standard output

This environment variable can be used to select the unit number preconnected to standard output. This must be a positive integer. The default value is 6.

3.3 GFORTRAN_STDERR_UNIT—Unit number for standard error

This environment variable can be used to select the unit number preconnected to standard error. This must be a positive integer. The default value is 0.

3.4 GFORTRAN_USE_STDERR—Send library output to standard error

This environment variable controls where library output is sent. If the first letter is ‘y’, ‘Y’ or ‘1’, standard error is used. If the first letter is ‘n’, ‘N’ or ‘0’, standard output is used.

3.5 GFORTRAN_TMPDIR—Directory for scratch files

This environment variable controls where scratch files are created. If this environment variable is missing, GNU Fortran searches for the environment variable TMP. If this is also missing, the default is ‘/tmp’.

3.6 GFORTRAN_UNBUFFERED_ALL—Don’t buffer I/O on all units

This environment variable controls whether all I/O is unbuffered. If the first letter is ‘y’,

‘Y’ or ‘1’, all I/O is unbuffered. This will slow down small sequential reads and writes. If the first letter is ‘n’, ‘N’ or ‘0’, I/O is buffered. This is the default.

3.7 GFORTRAN_UNBUFFERED_PRECONNECTED—Don’t buffer I/O on preconnected units

The environment variable named GFORTRAN_UNBUFFERED_PRECONNECTED controls whether

I/O on a preconnected unit (i.e STDOUT or STDERR) is unbuffered. If the first letter is

‘y’, ‘Y’ or ‘1’, I/O is unbuffered. This will slow down small sequential reads and writes. If the first letter is ‘n’, ‘N’ or ‘0’, I/O is buffered. This is the default.

3.8 GFORTRAN_SHOW_LOCUS—Show location for runtime errors

If the first letter is ‘y’, ‘Y’ or ‘1’, filename and line numbers for runtime errors are printed.

If the first letter is ‘n’, ‘N’ or ‘0’, don’t print filename and line numbers for runtime errors.

The default is to print the location.

20 The GNU Fortran Compiler

3.9 GFORTRAN_OPTIONAL_PLUS—Print leading + where permitted

If the first letter is ‘y’, ‘Y’ or ‘1’, a plus sign is printed where permitted by the Fortran standard. If the first letter is ‘n’, ‘N’ or ‘0’, a plus sign is not printed in most cases. Default is not to print plus signs.

3.10 GFORTRAN_DEFAULT_RECL—Default record length for new files

This environment variable specifies the default record length, in bytes, for files which are opened without a RECL tag in the OPEN statement. This must be a positive integer. The default value is 1073741824 bytes (1 GB).

3.11 GFORTRAN_LIST_SEPARATOR—Separator for list output

This environment variable specifies the separator when writing list-directed output. It may contain any number of spaces and at most one comma. If you specify this on the command line, be sure to quote spaces, as in

$ GFORTRAN_LIST_SEPARATOR=’ , ’ ./a.out

when a.out is the compiled Fortran program that you want to run. Default is a single space.

3.12 GFORTRAN_CONVERT_UNIT—Set endianness for unformatted

I/O

By setting the GFORTRAN_CONVERT_UNIT variable, it is possible to change the representation of data for unformatted files. The syntax for the GFORTRAN_CONVERT_UNIT variable is:

The variable consists of an optional default mode, followed by a list of optional exceptions, which are separated by semicolons from the preceding default and each other. Each exception consists of a format and a comma-separated list of units. Valid values for the modes are the same as for the CONVERT specifier:

NATIVE Use the native format. This is the default.

SWAP Swap between little- and big-endian.

LITTLE_ENDIAN Use the little-endian format for unformatted files.

BIG_ENDIAN Use the big-endian format for unformatted files.

A missing mode for an exception is taken to mean BIG_ENDIAN. Examples of values for

GFORTRAN_CONVERT_UNIT are:

’big_endian’ Do all unformatted I/O in big endian mode.

’little_endian;native:10-20,25’ Do all unformatted I/O in little endian mode, except for units 10 to 20 and 25, which are in native format.

’10-20’ Units 10 to 20 are big-endian, the rest is native.

Chapter 3: Runtime: Influencing runtime behavior with environment variables 21

Setting the environment variables should be done on the command line or via the export command for sh-compatible shells and via setenv for csh-compatible shells.

Example for sh:

$ gfortran foo.f90

$ GFORTRAN_CONVERT_UNIT=’big_endian;native:10-20’ ./a.out

Example code for csh:

% gfortran foo.f90

% setenv GFORTRAN_CONVERT_UNIT ’big_endian;native:10-20’

% ./a.out

Using anything but the native representation for unformatted data carries a significant speed overhead. If speed in this area matters to you, it is best if you use this only for data that needs to be portable.

See

Section 5.1.14 [CONVERT specifier], page 33 , for an alternative way to specify the

data representation for unformatted files. See

Section 2.7 [Runtime Options], page 14 , for

setting a default data representation for the whole program. The CONVERT specifier overrides the ‘-fconvert’ compile options.

Note that the values specified via the GFORTRAN CONVERT UNIT environment variable will override the CONVERT specifier in the open statement. This is to give control over data formats to users who do not have the source code of their program available.

3.13 GFORTRAN_ERROR_DUMPCORE—Dump core on run-time errors

If the GFORTRAN_ERROR_DUMPCORE variable is set to ‘y’, ‘Y’ or ‘1’ (only the first letter is relevant) then library run-time errors cause core dumps. To disable the core dumps, set the variable to ‘n’, ‘N’, ‘0’. Default is not to core dump unless the ‘-fdump-core’ compile option was used.

3.14 GFORTRAN_ERROR_BACKTRACE—Show backtrace on run-time errors

If the GFORTRAN_ERROR_BACKTRACE variable is set to ‘y’, ‘Y’ or ‘1’ (only the first letter is relevant) then a backtrace is printed when a run-time error occurs.

To disable the backtracing, set the variable to ‘n’, ‘N’, ‘0’. Default is not to print a backtrace unless the

‘-fbacktrace’ compile option was used.

Chapter 3: Runtime: Influencing runtime behavior with environment variables 23

Part II: Language Reference

Chapter 4: Fortran 2003 Status 25

4 Fortran 2003 Status

Although GNU Fortran focuses on implementing the Fortran 95 standard for the time being, a few Fortran 2003 features are currently available.

• Intrinsics command_argument_count, get_command, get_command_argument, get_environment_variable, and move_alloc.

• Array constructors using square brackets. That is, [...] rather than (/.../).

• FLUSH statement.

• IOMSG= specifier for I/O statements.

• Support for the declaration of enumeration constants via the ENUM and ENUMERATOR statements.

Interoperability with gcc is guaranteed also for the case where the fshort-enums command line option is given.

• TR 15581:

• ALLOCATABLE dummy arguments.

• ALLOCATABLE function results

• ALLOCATABLE components of derived types

• The OPEN statement supports the ACCESS=’STREAM’ specifier, allowing I/O without any record structure.

• Namelist input/output for internal files.

• The PROTECTED statement and attribute.

• The VALUE statement and attribute.

• The VOLATILE statement and attribute.

• The IMPORT statement, allowing to import host-associated derived types.

• USE statement with INTRINSIC and NON_INTRINSIC attribute; supported intrinsic modules: ISO_FORTRAN_ENV, OMP_LIB and OMP_LIB_KINDS.

• Renaming of operators in the USE statement.

• Interoperability with C (ISO C Bindings)

• BOZ as argument of INT, REAL, DBLE and CMPLX.

Chapter 5: Extensions 27

5 Extensions

The two sections below detail the extensions to standard Fortran that are implemented in

GNU Fortran, as well as some of the popular or historically important extensions that are not (or not yet) implemented. For the latter case, we explain the alternatives available to

GNU Fortran users, including replacement by standard-conforming code or GNU extensions.

5.1 Extensions implemented in GNU Fortran

GNU Fortran implements a number of extensions over standard Fortran. This chapter contains information on their syntax and meaning. There are currently two categories of

GNU Fortran extensions, those that provide functionality beyond that provided by any standard, and those that are supported by GNU Fortran purely for backward compatibility with legacy compilers. By default, ‘-std=gnu’ allows the compiler to accept both types of extensions, but to warn about the use of the latter. Specifying either ‘-std=f95’ or

‘-std=f2003’ disables both types of extensions, and ‘-std=legacy’ allows both without warning.

5.1.1 Old-style kind specifications

GNU Fortran allows old-style kind specifications in declarations. These look like:

TYPESPEC*size x,y,z where TYPESPEC is a basic type (INTEGER, REAL, etc.), and where size is a byte count corresponding to the storage size of a valid kind for that type. (For COMPLEX variables, size is the total size of the real and imaginary parts.) The statement then declares x, y and z to be of type TYPESPEC with the appropriate kind. This is equivalent to the standardconforming declaration

TYPESPEC(k) x,y,z where k is equal to size for most types, but is equal to size/2 for the COMPLEX type.

5.1.2 Old-style variable initialization

GNU Fortran allows old-style initialization of variables of the form:

INTEGER i/1/,j/2/

REAL x(2,2) /3*0.,1./

The syntax for the initializers is as for the DATA statement, but unlike in a DATA statement, an initializer only applies to the variable immediately preceding the initialization. In other words, something like INTEGER I,J/2,3/ is not valid. This style of initialization is only allowed in declarations without double colons (::); the double colons were introduced in Fortran 90, which also introduced a standard syntax for initializing variables in type declarations.

Examples of standard-conforming code equivalent to the above example are:

! Fortran 90

INTEGER :: i = 1, j = 2

REAL :: x(2,2) = RESHAPE((/0.,0.,0.,1./),SHAPE(x))

! Fortran 77

INTEGER i, j

REAL x(2,2)

DATA i/1/, j/2/, x/3*0.,1./

28 The GNU Fortran Compiler

Note that variables which are explicitly initialized in declarations or in DATA statements automatically acquire the SAVE attribute.

5.1.3 Extensions to namelist

GNU Fortran fully supports the Fortran 95 standard for namelist I/O including array qualifiers, substrings and fully qualified derived types. The output from a namelist write is compatible with namelist read. The output has all names in upper case and indentation to column 1 after the namelist name. Two extensions are permitted:

Old-style use of ‘$’ instead of ‘&’

$MYNML

X(:)%Y(2) = 1.0 2.0 3.0

CH(1:4) = "abcd"

$END

It should be noted that the default terminator is ‘/’ rather than ‘&END’.

Querying of the namelist when inputting from stdin. After at least one space, entering

‘?’ sends to stdout the namelist name and the names of the variables in the namelist:

&mynml x x%y ch

&end

Entering ‘=?’ outputs the namelist to stdout, as if WRITE(*,NML = mynml) had been called:

&MYNML

X(1)%Y= 0.000000

X(2)%Y= 0.000000

X(3)%Y= 0.000000

CH=abcd, /

, 1.000000

, 2.000000

, 3.000000

, 0.000000

To aid this dialog, when input is from stdin, errors send their messages to stderr and execution continues, even if IOSTAT is set.

PRINT namelist is permitted. This causes an error if ‘-std=f95’ is used.

PROGRAM test_print

REAL, dimension (4) :: x = (/1.0, 2.0, 3.0, 4.0/)

NAMELIST /mynml/ x

PRINT mynml

END PROGRAM test_print

Expanded namelist reads are permitted. This causes an error if ‘-std=f95’ is used. In the following example, the first element of the array will be given the value 0.00 and the two succeeding elements will be given the values 1.00 and 2.00.

&MYNML

X(1,1) = 0.00 , 1.00 , 2.00

Chapter 5: Extensions 29

5.1.4 X format descriptor without count field

To support legacy codes, GNU Fortran permits the count field of the X edit descriptor in

FORMAT statements to be omitted. When omitted, the count is implicitly assumed to be one.

PRINT 10, 2, 3

FORMAT (I1, X, I1)

5.1.5 Commas in FORMAT specifications

To support legacy codes, GNU Fortran allows the comma separator to be omitted immediately before and after character string edit descriptors in FORMAT statements.

PRINT 10, 2, 3

FORMAT (’FOO=’I1’ BAR=’I2)

5.1.6 Missing period in FORMAT specifications

To support legacy codes, GNU Fortran allows missing periods in format specifications if and only if ‘-std=legacy’ is given on the command line. This is considered non-conforming code and is discouraged.

REAL :: value

READ(*,10) value

FORMAT (’F4’)

5.1.7 I/O item lists

To support legacy codes, GNU Fortran allows the input item list of the READ statement, and the output item lists of the WRITE and PRINT statements, to start with a comma.

5.1.8 BOZ literal constants

Besides decimal constants, Fortran also supports binary (b), octal (o) and hexadecimal (z) integer constants. The syntax is: ‘prefix quote digits quote’, were the prefix is either b, o or z, quote is either ’ or " and the digits are for binary 0 or 1, for octal between 0 and

7, and for hexadecimal between 0 and F. (Example: b’01011101’.)

Up to Fortran 95, BOZ literals were only allowed to initialize integer variables in DATA statements. Since Fortran 2003 BOZ literals are also allowed as argument of REAL, DBLE,

INT and CMPLX; the result is the same as if the integer BOZ literal had been converted by

TRANSFER to, respectively, real, double precision, integer or complex. As GNU Fortran extension the intrinsic procedures FLOAT, DFLOAT, COMPLEX and DCMPLX are treated alike.

As an extension, GNU Fortran allows hexadecimal BOZ literal constants to be specified using the X prefix, in addition to the standard Z prefix. The BOZ literal can also be specified by adding a suffix to the string, for example, Z’ABC’ and ’ABC’Z are equivalent.

Furthermore, GNU Fortran allows using BOZ literal constants outside DATA statements and the four intrinsic functions allowed by Fortran 2003. In DATA statements, in direct assignments, where the right-hand side only contains a BOZ literal constant, and for oldstyle initializers of the form integer i /o’0173’/, the constant is transferred as if TRANSFER had been used; for COMPLEX numbers, only the real part is initialized unless CMPLX is used.

In all other cases, the BOZ literal constant is converted to an INTEGER value with the largest decimal representation. This value is then converted numerically to the type and kind of the variable in question. (For instance real :: r = b’0000001’ + 1 initializes r with 2.0.) As

30 The GNU Fortran Compiler different compilers implement the extension differently, one should be careful when doing bitwise initialization of non-integer variables.

Note that initializing an

INTEGER variable with a statement such as

DATA i/Z’FFFFFFFF’/ will give an integer overflow error rather than the desired result of −1 when i is a 32-bit integer on a system that supports 64-bit integers.

The

‘-fno-range-check’ option can be used as a workaround for legacy code that initializes integers in this manner.

5.1.9 Real array indices

As an extension, GNU Fortran allows the use of REAL expressions or variables as array indices.

5.1.10 Unary operators

As an extension, GNU Fortran allows unary plus and unary minus operators to appear as the second operand of binary arithmetic operators without the need for parenthesis.

X = Y * -Z

5.1.11 Implicitly convert LOGICAL and INTEGER values

As an extension for backwards compatibility with other compilers, GNU Fortran allows the implicit conversion of LOGICAL values to INTEGER values and vice versa. When converting from a LOGICAL to an INTEGER, .FALSE. is interpreted as zero, and .TRUE. is interpreted as one. When converting from INTEGER to LOGICAL, the value zero is interpreted as .FALSE.

and any nonzero value is interpreted as .TRUE..

LOGICAL :: l l = 1

INTEGER :: i i = .TRUE.

However, there is no implicit conversion of INTEGER values in if-statements, nor of

LOGICAL or INTEGER values in I/O operations.

5.1.12 Hollerith constants support

GNU Fortran supports Hollerith constants in assignments, function arguments, and DATA and ASSIGN statements. A Hollerith constant is written as a string of characters preceded by an integer constant indicating the character count, and the letter H or h, and stored in bytewise fashion in a numeric (INTEGER, REAL, or complex) or LOGICAL variable. The constant will be padded or truncated to fit the size of the variable in which it is stored.

Examples of valid uses of Hollerith constants: complex*16 x(2) data x /16Habcdefghijklmnop, 16Hqrstuvwxyz012345/ x(1) = 16HABCDEFGHIJKLMNOP call foo (4h abc)

Invalid Hollerith constants examples: integer*4 a a = 8H12345678 ! Valid, but the Hollerith constant will be truncated.

a = 0H ! At least one character is needed.

In general, Hollerith constants were used to provide a rudimentary facility for handling character strings in early Fortran compilers, prior to the introduction of CHARACTER variables

Chapter 5: Extensions 31 in Fortran 77; in those cases, the standard-compliant equivalent is to convert the program to use proper character strings. On occasion, there may be a case where the intent is specifically to initialize a numeric variable with a given byte sequence. In these cases, the same result can be obtained by using the TRANSFER statement, as in this example.

INTEGER(KIND=4) :: a a = TRANSFER ("abcd", a) ! equivalent to: a = 4Habcd

5.1.13 Cray pointers

Cray pointers are part of a non-standard extension that provides a C-like pointer in Fortran.

This is accomplished through a pair of variables: an integer "pointer" that holds a memory address, and a "pointee" that is used to dereference the pointer.

Pointer/pointee pairs are declared in statements of the form: pointer ( <pointer> , <pointee> ) or, pointer ( <pointer1> , <pointee1> ), ( <pointer2> , <pointee2> ), ...

The pointer is an integer that is intended to hold a memory address. The pointee may be an array or scalar. A pointee can be an assumed size array—that is, the last dimension may be left unspecified by using a * in place of a value—but a pointee cannot be an assumed shape array. No space is allocated for the pointee.

The pointee may have its type declared before or after the pointer statement, and its array specification (if any) may be declared before, during, or after the pointer statement.

The pointer may be declared as an integer prior to the pointer statement. However, some machines have default integer sizes that are different than the size of a pointer, and so the following code is not portable: integer ipt pointer (ipt, iarr)

If a pointer is declared with a kind that is too small, the compiler will issue a warning; the resulting binary will probably not work correctly, because the memory addresses stored in the pointers may be truncated. It is safer to omit the first line of the above example; if explicit declaration of ipt’s type is omitted, then the compiler will ensure that ipt is an integer variable large enough to hold a pointer.

Pointer arithmetic is valid with Cray pointers, but it is not the same as C pointer arithmetic. Cray pointers are just ordinary integers, so the user is responsible for determining how many bytes to add to a pointer in order to increment it. Consider the following example: real target(10) real pointee(10) pointer (ipt, pointee) ipt = loc (target) ipt = ipt + 1

The last statement does not set ipt to the address of target(1), as it would in C pointer arithmetic. Adding 1 to ipt just adds one byte to the address stored in ipt.

Any expression involving the pointee will be translated to use the value stored in the pointer as the base address.

To get the address of elements, this extension provides an intrinsic function LOC(). The

LOC() function is equivalent to the & operator in C, except the address is cast to an integer type:

32 The GNU Fortran Compiler real ar(10) pointer(ipt, arpte(10)) real arpte ipt = loc(ar) ! Makes arpte is an alias for ar arpte(1) = 1.0 ! Sets ar(1) to 1.0

The pointer can also be set by a call to the MALLOC intrinsic (see

Section 6.141 [MALLOC], page 116 ).

Cray pointees often are used to alias an existing variable. For example: integer target(10) integer iarr(10) pointer (ipt, iarr) ipt = loc(target)

As long as ipt remains unchanged, iarr is now an alias for target. The optimizer, however, will not detect this aliasing, so it is unsafe to use iarr and target simultaneously.

Using a pointee in any way that violates the Fortran aliasing rules or assumptions is illegal.

It is the user’s responsibility to avoid doing this; the compiler works under the assumption that no such aliasing occurs.

Cray pointers will work correctly when there is no aliasing (i.e., when they are used to access a dynamically allocated block of memory), and also in any routine where a pointee is used, but any variable with which it shares storage is not used. Code that violates these rules may not run as the user intends. This is not a bug in the optimizer; any code that violates the aliasing rules is illegal. (Note that this is not unique to GNU Fortran; any

Fortran compiler that supports Cray pointers will “incorrectly” optimize code with illegal aliasing.)

There are a number of restrictions on the attributes that can be applied to Cray pointers and pointees. Pointees may not have the ALLOCATABLE, INTENT, OPTIONAL, DUMMY, TARGET,

INTRINSIC, or POINTER attributes. Pointers may not have the DIMENSION, POINTER, TARGET,

ALLOCATABLE, EXTERNAL, or INTRINSIC attributes. Pointees may not occur in more than one pointer statement. A pointee cannot be a pointer. Pointees cannot occur in equivalence, common, or data statements.

A Cray pointer may also point to a function or a subroutine. For example, the following excerpt is valid: implicit none external sub pointer (subptr,subpte) external subpte subptr = loc(sub) call subpte()

[...] subroutine sub

[...] end subroutine sub

A pointer may be modified during the course of a program, and this will change the location to which the pointee refers. However, when pointees are passed as arguments, they are treated as ordinary variables in the invoked function. Subsequent changes to the pointer will not change the base address of the array that was passed.

Chapter 5: Extensions 33

5.1.14 CONVERT specifier

GNU Fortran allows the conversion of unformatted data between little- and big-endian representation to facilitate moving of data between different systems. The conversion can be indicated with the CONVERT specifier on the OPEN statement. See

Section 3.12 [GFOR-

TRAN CONVERT UNIT], page 20 , for an alternative way of specifying the data format

via an environment variable.

Valid values for CONVERT are:

CONVERT=’NATIVE’ Use the native format. This is the default.

CONVERT=’SWAP’ Swap between little- and big-endian.

CONVERT=’LITTLE_ENDIAN’ Use the little-endian representation for unformatted files.

CONVERT=’BIG_ENDIAN’ Use the big-endian representation for unformatted files.

Using the option could look like this: open(file=’big.dat’,form=’unformatted’,access=’sequential’, & convert=’big_endian’)

The value of the conversion can be queried by using INQUIRE(CONVERT=ch). The values returned are ’BIG_ENDIAN’ and ’LITTLE_ENDIAN’.

CONVERT works between big- and little-endian for INTEGER values of all supported kinds and for REAL on IEEE systems of kinds 4 and 8. Conversion between different “extended double” types on different architectures such as m68k and x86 64, which GNU Fortran supports as REAL(KIND=10) and REAL(KIND=16), will probably not work.

5.1.15 OpenMP

OpenMP (Open Multi-Processing) is an application programming interface (API) that supports multi-platform shared memory multiprocessing programming in C/C++ and Fortran on many architectures, including Unix and Microsoft Windows platforms. It consists of a set of compiler directives, library routines, and environment variables that influence run-time behavior.

GNU Fortran strives to be compatible to the OpenMP Application Program Interface v2.5

To enable the processing of the OpenMP directive !$omp in free-form source code; the c$omp, *$omp and !$omp directives in fixed form; the !$ conditional compilation sentinels in free form; and the c$, *$ and !$ sentinels in fixed form, gfortran needs to be invoked with the ‘-fopenmp’. This also arranges for automatic linking of the GNU OpenMP runtime library Section “libgomp” in GNU OpenMP runtime library .

The OpenMP Fortran runtime library routines are provided both in a form of a Fortran

90 module named omp_lib and in a form of a Fortran include file named ‘omp_lib.h’.

An example of a parallelized loop taken from Appendix A.1 of the OpenMP Application

Program Interface v2.5:

34 The GNU Fortran Compiler

SUBROUTINE A1(N, A, B)

INTEGER I, N

REAL B(N), A(N)

!$OMP PARALLEL DO !I is private by default

DO I=2,N

B(I) = (A(I) + A(I-1)) / 2.0

ENDDO

!$OMP END PARALLEL DO

END SUBROUTINE A1

Please note:

• ‘-fopenmp’ implies ‘-frecursive’, i.e. all local arrays will be allocated on the stack.

When porting existing code to OpenMP, this may lead to surprising results, especially to segmentation faults if the stacksize is limited.

• On glibc-based systems, OpenMP enabled applications can not be statically linked due to limitations of the underlying pthreads-implementation. It might be possible to get a working solution if -Wl,--whole-archive -lpthread -Wl,--no-whole-archive is added to the command line. However, this is not supported by gcc and thus not recommended.

5.1.16 Argument list functions %VAL, %REF and %LOC

GNU Fortran supports argument list functions %VAL, %REF and %LOC statements, for backward compatibility with g77. It is recommended that these should be used only for code that is accessing facilities outside of GNU Fortran, such as operating system or windowing facilities. It is best to constrain such uses to isolated portions of a program–portions that deal specifically and exclusively with low-level, system-dependent facilities. Such portions might well provide a portable interface for use by the program as a whole, but are themselves not portable, and should be thoroughly tested each time they are rebuilt using a new compiler or version of a compiler.

%VAL passes a scalar argument by value, %REF passes it by reference and %LOC passes its memory location. Since gfortran already passes scalar arguments by reference, %REF is in effect a do-nothing. %LOC has the same effect as a fortran pointer.

An example of passing an argument by value to a C subroutine foo.:

C prototype

C void foo_ (float x); external foo real*4 x x = 3.14159

call foo (%VAL (x)) end

For details refer to the g77 manual http://gcc.gnu.org/onlinedocs/gcc-3.4.6/g77/index.html#Top

Also, the gfortran testsuite c by val.f and its partner c by val.c are worth a look.

5.2 Extensions not implemented in GNU Fortran

The long history of the Fortran language, its wide use and broad userbase, the large number of different compiler vendors and the lack of some features crucial to users in the first standards have lead to the existence of an important number of extensions to the language.

While some of the most useful or popular extensions are supported by the GNU Fortran

Chapter 5: Extensions 35 compiler, not all existing extensions are supported. This section aims at listing these extensions and offering advice on how best make code that uses them running with the GNU

Fortran compiler.

5.2.1 STRUCTURE and RECORD

Structures are user-defined aggregate data types; this functionality was standardized in

Fortran 90 with an different syntax, under the name of “derived types”. Here is an example of code using the non portable structure syntax:

! Declaring a structure named ‘‘item’’ and containing three fields:

! an integer ID, an description string and a floating-point price.

STRUCTURE /item/

INTEGER id

CHARACTER(LEN=200) description

REAL price

END STRUCTURE

! Define two variables, an single record of type ‘‘item’’

! named ‘‘pear’’, and an array of items named ‘‘store_catalog’’

RECORD /item/ pear, store_catalog(100)

! We can directly access the fields of both variables pear.id = 92316 pear.description = "juicy D’Anjou pear" pear.price = 0.15

store_catalog(7).id = 7831 store_catalog(7).description = "milk bottle" store_catalog(7).price = 1.2

! We can also manipulates the whole structure store_catalog(12) = pear print *, store_catalog(12)

This code can easily be rewritten in the Fortran 90 syntax as following:

! ‘‘STRUCTURE /name/ ... END STRUCTURE’’ becomes

! ‘‘TYPE name ... END TYPE’’

TYPE item

INTEGER id

CHARACTER(LEN=200) description

REAL price

END TYPE

! ‘‘RECORD /name/ variable’’ becomes ‘‘TYPE(name) variable’’

TYPE(item) pear, store_catalog(100)

! Instead of using a dot (.) to access fields of a record, the

! standard syntax uses a percent sign (%) pear%id = 92316

36 The GNU Fortran Compiler pear%description = "juicy D’Anjou pear" pear%price = 0.15

store_catalog(7)%id = 7831 store_catalog(7)%description = "milk bottle" store_catalog(7)%price = 1.2

! Assignments of a whole variable don’t change store_catalog(12) = pear print *, store_catalog(12)

5.2.2 ENCODE and DECODE statements

GNU Fortran doesn’t support the ENCODE and DECODE statements. These statements are best replaced by READ and WRITE statements involving internal files (CHARACTER variables and arrays), which have been part of the Fortran standard since Fortran 77. For example, replace a code fragment like

INTEGER*1 LINE(80)

REAL A, B, C

... Code that sets LINE c

DECODE (80, 9000, LINE) A, B, C

9000 FORMAT (1X, 3(F10.5)) with the following:

CHARACTER(LEN=80) LINE

REAL A, B, C c ... Code that sets LINE

READ (UNIT=LINE, FMT=9000) A, B, C

9000 FORMAT (1X, 3(F10.5))

Similarly, replace a code fragment like

INTEGER*1 LINE(80)

REAL A, B, C c ... Code that sets A, B and C

ENCODE (80, 9000, LINE) A, B, C

9000 FORMAT (1X, ’OUTPUT IS ’, 3(F10.5)) with the following:

INTEGER*1 LINE(80)

REAL A, B, C

... Code that sets A, B and C c

WRITE (UNIT=LINE, FMT=9000) A, B, C

9000 FORMAT (1X, ’OUTPUT IS ’, 3(F10.5))

Chapter 6: Intrinsic Procedures 37

6 Intrinsic Procedures

6.1 Introduction to intrinsic procedures

The intrinsic procedures provided by GNU Fortran include all of the intrinsic procedures required by the Fortran 95 standard, a set of intrinsic procedures for backwards compatibility with G77, and a small selection of intrinsic procedures from the Fortran 2003 standard.

Any conflict between a description here and a description in either the Fortran 95 standard or the Fortran 2003 standard is unintentional, and the standard(s) should be considered authoritative.

The enumeration of the KIND type parameter is processor defined in the Fortran

95 standard.

GNU Fortran defines the default integer type and default real type by

INTEGER(KIND=4) and REAL(KIND=4), respectively. The standard mandates that both data types shall have another kind, which have more precision. On typical target architectures supported by gfortran, this kind type parameter is KIND=8. Hence, REAL(KIND=8) and

DOUBLE PRECISION are equivalent.

In the description of generic intrinsic procedures, the kind type parameter will be specified by KIND=*, and in the description of specific names for an intrinsic procedure the kind type parameter will be explicitly given (e.g.,

REAL(KIND=4) or REAL(KIND=8)). Finally, for brevity the optional KIND= syntax will be omitted.

Many of the intrinsic procedures take one or more optional arguments. This document follows the convention used in the Fortran 95 standard, and denotes such arguments by square brackets.

GNU Fortran offers the ‘-std=f95’ and ‘-std=gnu’ options, which can be used to restrict the set of intrinsic procedures to a given standard. By default, gfortran sets the ‘-std=gnu’ option, and so all intrinsic procedures described here are accepted. There is one caveat. For a select group of intrinsic procedures, g77 implemented both a function and a subroutine.

Both classes have been implemented in gfortran for backwards compatibility with g77. It is noted here that these functions and subroutines cannot be intermixed in a given subprogram.

In the descriptions that follow, the applicable standard for each intrinsic procedure is noted.

6.2 ABORT — Abort the program

Description:

ABORT causes immediate termination of the program. On operating systems that support a core dump, ABORT will produce a core dump, which is suitable for debugging purposes.

Standard : GNU extension

Class: Subroutine

Syntax :

CALL ABORT

Return value:

Does not return.

Example:

38 The GNU Fortran Compiler program test_abort integer :: i = 1, j = 2 if (i /= j) call abort end program test_abort

See also:

Section 6.66 [EXIT], page 77 ,

Section 6.121 [KILL], page 106

6.3 ABS — Absolute value

Description:

ABS(X) computes the absolute value of X.

Standard : F77 and later, has overloads that are GNU extensions

Class: Elemental function

Syntax :

RESULT = ABS(X)

Arguments:

X The type of the argument shall be an INTEGER(*), REAL(*), or COMPLEX(*).

Return value:

The return value is of the same type and kind as the argument except the return value is REAL(*) for a COMPLEX(*) argument.

Example:

Specific names:

Name

CABS(Z)

DABS(X)

IABS(I)

ZABS(Z)

CDABS(Z) program test_abs integer :: i = -1 real :: x = -1.e0

complex :: z = (-1.e0,0.e0) i = abs(i) x = abs(x) x = abs(z) end program test_abs

Argument Return type

COMPLEX(4) Z REAL(4)

REAL(8) X REAL(8)

INTEGER(4) I INTEGER(4)

COMPLEX(8) Z COMPLEX(8)

Standard

F77 and later

GNU extension

6.4 ACCESS — Checks file access modes

Description:

ACCESS(NAME, MODE) checks whether the file NAME exists, is readable, writable or executable. Except for the executable check, ACCESS can be replaced by

Fortran 95’s INQUIRE.

Standard : GNU extension

Class: Inquiry function

Syntax :

RESULT = ACCESS(NAME, MODE)

Chapter 6: Intrinsic Procedures 39

Arguments:

NAME

MODE

Scalar CHARACTER with the file name. Tailing blank are ignored unless the character achar(0) is present, then all characters up to and excluding achar(0) are used as file name.

Scalar CHARACTER with the file access mode, may be any concatenation of "r" (readable), "w" (writable) and "x" (executable), or " " to check for existence.

Return value:

Returns a scalar INTEGER, which is 0 if the file is accessible in the given mode; otherwise or if an invalid argument has been given for MODE the value 1 is returned.

Example: program access_test implicit none character(len=*), parameter :: file = ’test.dat’ character(len=*), parameter :: file2 = ’test.dat

’//achar(0) if(access(file,’ ’) == 0) print *, trim(file),’ is exists’ if(access(file,’r’) == 0) print *, trim(file),’ is readable’ if(access(file,’w’) == 0) print *, trim(file),’ is writable’ if(access(file,’x’) == 0) print *, trim(file),’ is executable’ if(access(file2,’rwx’) == 0) & print *, trim(file2),’ is readable, writable and executable’ end program access_test

Specific names:

See also:

6.5 ACHAR — Character in

ASCII collating sequence

Description:

ACHAR(I) returns the character located at position I in the

ASCII collating sequence.

Standard : F77 and later

Class:

Syntax :

Elemental function

RESULT = ACHAR(I)

Arguments:

I The type shall be INTEGER(*).

Return value:

The return value is of type CHARACTER with a length of one. The kind type parameter is the same as KIND(’A’).

Example: program test_achar character c c = achar(32) end program test_achar

Note: See

Section 6.104 [ICHAR], page 97

for a discussion of converting between numerical values and formatted string representations.

40 The GNU Fortran Compiler

See also:

Section 6.38 [CHAR], page 59 ,

Section 6.98 [IACHAR], page 94

Section 6.104

[ICHAR], page 97

6.6 ACOS — Arccosine function

Description:

ACOS(X) computes the arccosine of X (inverse of COS(X)).

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = ACOS(X)

Arguments:

X The type shall be REAL(*) with a magnitude that is less than one.

Return value:

The return value is of type REAL(*) and it lies in the range 0 ≤ acos(x) ≤ π.

The kind type parameter is the same as X.

Example: program test_acos real(8) :: x = 0.866_8

x = acos(x) end program test_acos

Specific names:

Name

DACOS(X)

Argument

REAL(8) X

Return type

REAL(8)

See also: Inverse function:

Section 6.45 [COS], page 63

Standard

F77 and later

6.7 ACOSH — Hyperbolic arccosine function

Description:

ACOSH(X) computes the hyperbolic arccosine of X (inverse of COSH(X)).

Standard : GNU extension

Class: Elemental function

Syntax :

RESULT = ACOSH(X)

Arguments:

X The type shall be REAL(*) with a magnitude that is greater or equal to one.

Return value:

The return value is of type REAL(*) and it lies in the range 0 ≤ acosh(x) ≤ ∞.

Example:

PROGRAM test_acosh

REAL(8), DIMENSION(3) :: x = (/ 1.0, 2.0, 3.0 /)

WRITE (*,*) ACOSH(x)

END PROGRAM

Chapter 6: Intrinsic Procedures 41

Specific names:

Name

DACOSH(X)

Argument

REAL(8) X

Return type

REAL(8)

See also: Inverse function:

Section 6.46 [COSH], page 64

Standard

GNU extension

6.8 ADJUSTL — Left adjust a string

Description:

ADJUSTL(STR) will left adjust a string by removing leading spaces. Spaces are inserted at the end of the string as needed.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = ADJUSTL(STR)

Arguments:

STR The type shall be CHARACTER.

Return value:

The return value is of type CHARACTER where leading spaces are removed and the same number of spaces are inserted on the end of STR.

Example: program test_adjustl character(len=20) :: str = ’ gfortran’ str = adjustl(str) print *, str end program test_adjustl

See also:

Section 6.9 [ADJUSTR], page 41

Section 6.213 [TRIM], page 157

6.9 ADJUSTR — Right adjust a string

Description:

ADJUSTR(STR) will right adjust a string by removing trailing spaces. Spaces are inserted at the start of the string as needed.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = ADJUSTR(STR)

Arguments:

STR The type shall be CHARACTER.

Return value:

The return value is of type CHARACTER where trailing spaces are removed and the same number of spaces are inserted at the start of STR.

Example:

42 The GNU Fortran Compiler program test_adjustr character(len=20) :: str = ’gfortran’ str = adjustr(str) print *, str end program test_adjustr

See also:

Section 6.213 [TRIM], page 157

6.10 AIMAG — Imaginary part of complex number

Description:

AIMAG(Z) yields the imaginary part of complex argument Z. The IMAG(Z) and

IMAGPART(Z) intrinsic functions are provided for compatibility with g77, and their use in new code is strongly discouraged.

Standard : F77 and later, has overloads that are GNU extensions

Class:

Syntax :

Elemental function

RESULT = AIMAG(Z)

Arguments:

Z The type of the argument shall be COMPLEX(*).

Return value:

The return value is of type real with the kind type parameter of the argument.

Example: program test_aimag complex(4) z4 complex(8) z8 z4 = cmplx(1.e0_4, 0.e0_4) z8 = cmplx(0.e0_8, 1.e0_8) print *, aimag(z4), dimag(z8) end program test_aimag

Specific names:

Name

DIMAG(Z)

IMAG(Z)

IMAGPART(Z)

Argument

COMPLEX(8) Z

COMPLEX(*) Z

Return type

REAL(8)

REAL(*)

Standard

GNU extension

6.11 AINT — Truncate to a whole number

Description:

AINT(X [, KIND]) truncates its argument to a whole number.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = AINT(X [, KIND])

Arguments:

KIND

The type of the argument shall be REAL(*).

(Optional) An INTEGER(*) initialization expression indicating the kind parameter of the result.

Chapter 6: Intrinsic Procedures 43

Return value:

The return value is of type real with the kind type parameter of the argument if the optional KIND is absent; otherwise, the kind type parameter will be given by KIND. If the magnitude of X is less than one, then AINT(X) returns zero. If the magnitude is equal to or greater than one, then it returns the largest whole number that does not exceed its magnitude. The sign is the same as the sign of X.

Example: program test_aint real(4) x4 real(8) x8 x4 = 1.234E0_4

x8 = 4.321_8

print *, aint(x4), dint(x8) x8 = aint(x4,8) end program test_aint

Specific names:

Name

DINT(X)

Argument

REAL(8) X

Return type

REAL(8)

Standard

F77 and later

6.12 ALARM — Execute a routine after a given delay

Description:

ALARM(SECONDS, HANDLER [, STATUS]) causes external subroutine HANDLER to be executed after a delay of SECONDS by using alarm(2) to set up a signal and signal(2) to catch it. If STATUS is supplied, it will be returned with the number of seconds remaining until any previously scheduled alarm was due to be delivered, or zero if there was no previously scheduled alarm.

Standard : GNU extension

Class: Subroutine

Syntax :

CALL ALARM(SECONDS, HANDLER [, STATUS])

Arguments:

SECONDS

HANDLER

STATUS

The type of the argument shall be a scalar INTEGER. It is

INTENT(IN).

Signal handler (INTEGER FUNCTION or

SUBROUTINE) or dummy/global INTEGER scalar. The scalar values may be either SIG_IGN=1 to ignore the alarm generated or SIG_DFL=0 to set the default action. It is INTENT(IN).

(Optional) STATUS shall be a scalar variable of the default

INTEGER kind. It is INTENT(OUT).

Example: program test_alarm external handler_print integer i call alarm (3, handler_print, i) print *, i

44 The GNU Fortran Compiler call sleep(10) end program test_alarm

This will cause the external routine handler print to be called after 3 seconds.

6.13 ALL — All values in MASK along DIM are true

Description:

ALL(MASK [, DIM]) determines if all the values are true in MASK in the array along dimension DIM.

Standard : F95 and later

Class: Transformational function

Syntax :

RESULT = ALL(MASK [, DIM])

Arguments:

MASK

DIM

The type of the argument shall be LOGICAL(*) and it shall not be scalar.

(Optional) DIM shall be a scalar integer with a value that lies between one and the rank of MASK.

Return value:

ALL(MASK) returns a scalar value of type LOGICAL(*) where the kind type parameter is the same as the kind type parameter of MASK. If DIM is present, then ALL(MASK, DIM) returns an array with the rank of MASK minus 1. The shape is determined from the shape of MASK where the DIM dimension is elided.

(A)

(B)

ALL(MASK) is true if all elements of MASK are true. It also is true if MASK has zero size; otherwise, it is false.

If the rank of MASK is one, then ALL(MASK,DIM) is equivalent to

ALL(MASK). If the rank is greater than one, then ALL(MASK,DIM) is determined by applying ALL to the array sections.

Example: program test_all logical l l = all((/.true., .true., .true./)) print *, l call section contains subroutine section integer a(2,3), b(2,3) a = 1 b = 1 b(2,2) = 2 print *, all(a .eq. b, 1) print *, all(a .eq. b, 2) end subroutine section end program test_all

Chapter 6: Intrinsic Procedures 45

6.14 ALLOCATED — Status of an allocatable entity

Description:

ALLOCATED(X) checks the status of whether X is allocated.

Standard : F95 and later

Class: Inquiry function

Syntax :

RESULT = ALLOCATED(X)

Arguments:

X The argument shall be an ALLOCATABLE array.

Return value:

The return value is a scalar LOGICAL with the default logical kind type parameter. If X is allocated, ALLOCATED(X) is .TRUE.; otherwise, it returns .FALSE.

Example: program test_allocated integer :: i = 4 real(4), allocatable :: x(:) if (allocated(x) .eqv. .false.) allocate(x(i)) end program test_allocated

6.15 AND — Bitwise logical AND

Description:

Bitwise logical AND.

This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. For integer arguments, programmers should consider the use of the

Section 6.99 [IAND], page 95

intrinsic defined by the Fortran standard.

Standard : GNU extension

Class:

Syntax :

Function

RESULT = AND(I, J)

Arguments:

Return value:

The return type is either INTEGER(*) or LOGICAL after cross-promotion of the arguments.

Example:

The type shall be either INTEGER(*) or LOGICAL.

PROGRAM test_and

LOGICAL :: T = .TRUE., F = .FALSE.

INTEGER :: a, b

DATA a / Z’F’ /, b / Z’3’ /

WRITE (*,*) AND(T, T), AND(T, F), AND(F, T), AND(F, F)

WRITE (*,*) AND(a, b)

END PROGRAM

6.16 ANINT — Nearest whole number

Description:

ANINT(X [, KIND]) rounds its argument to the nearest whole number.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = ANINT(X [, KIND])

Arguments:

KIND

Return value:

The return value is of type real with the kind type parameter of the argument if the optional KIND is absent; otherwise, the kind type parameter will be given by KIND. If X is greater than zero, then ANINT(X) returns AINT(X+0.5). If X is less than or equal to zero, then it returns AINT(X-0.5).

Example:

The type of the argument shall be REAL(*).

(Optional) An INTEGER(*) initialization expression indicating the kind parameter of the result.

program test_anint real(4) x4 real(8) x8 x4 = 1.234E0_4

x8 = 4.321_8

print *, anint(x4), dnint(x8) x8 = anint(x4,8) end program test_anint

Specific names:

Name

DNINT(X)

Argument

REAL(8) X

Return type

REAL(8)

Standard

F77 and later

6.17 ANY — Any value in MASK along DIM is true

Description:

ANY(MASK [, DIM]) determines if any of the values in the logical array MASK along dimension DIM are .TRUE..

Standard : F95 and later

Class:

Syntax :

Transformational function

RESULT = ANY(MASK [, DIM])

Arguments:

MASK

DIM

The type of the argument shall be LOGICAL(*) and it shall not be scalar.

(Optional) DIM shall be a scalar integer with a value that lies between one and the rank of MASK.

Chapter 6: Intrinsic Procedures 47

Return value:

ANY(MASK) returns a scalar value of type LOGICAL(*) where the kind type parameter is the same as the kind type parameter of MASK. If DIM is present, then ANY(MASK, DIM) returns an array with the rank of MASK minus 1. The shape is determined from the shape of MASK where the DIM dimension is elided.

(A)

(B)

ANY(MASK) is true if any element of MASK is true; otherwise, it is false. It also is false if MASK has zero size.

If the rank of MASK is one, then ANY(MASK,DIM) is equivalent to

ANY(MASK). If the rank is greater than one, then ANY(MASK,DIM) is determined by applying ANY to the array sections.

Example: program test_any logical l l = any((/.true., .true., .true./)) print *, l call section contains subroutine section integer a(2,3), b(2,3) a = 1 b = 1 b(2,2) = 2 print *, any(a .eq. b, 1) print *, any(a .eq. b, 2) end subroutine section end program test_any

6.18 ASIN — Arcsine function

Description:

ASIN(X) computes the arcsine of its X (inverse of SIN(X)).

Standard : F77 and later

Class:

Syntax :

Elemental function

RESULT = ASIN(X)

Arguments:

X The type shall be REAL(*), and a magnitude that is less than one.

Return value:

The return value is of type REAL(*) and it lies in the range −π/2 ≤ asin(x) ≤

π/2. The kind type parameter is the same as X.

Example: program test_asin real(8) :: x = 0.866_8

x = asin(x) end program test_asin

48 The GNU Fortran Compiler

Specific names:

Name

DASIN(X)

Argument

REAL(8) X

Return type

REAL(8)

See also: Inverse function:

Section 6.191 [SIN], page 144

Standard

F77 and later

6.19 ASINH — Hyperbolic arcsine function

Description:

ASINH(X) computes the hyperbolic arcsine of X (inverse of SINH(X)).

Standard : GNU extension

Class: Elemental function

Syntax :

RESULT = ASINH(X)

Arguments:

X The type shall be REAL(*), with X a real number.

Return value:

The return value is of type REAL(*) and it lies in the range −∞ ≤ asinh(x) ≤ ∞.

Example:

PROGRAM test_asinh

REAL(8), DIMENSION(3) :: x = (/ -1.0, 0.0, 1.0 /)

WRITE (*,*) ASINH(x)

END PROGRAM

Specific names:

Name

DASINH(X)

Argument

REAL(8) X

Return type

REAL(8)

See also: Inverse function:

Section 6.192 [SINH], page 145

Standard

GNU extension.

6.20 ASSOCIATED — Status of a pointer or pointer/target pair

Description:

ASSOCIATED(PTR [, TGT]) determines the status of the pointer PTR or if PTR is associated with the target TGT.

Standard : F95 and later

Class:

Syntax :

Inquiry function

RESULT = ASSOCIATED(PTR [, TGT])

Arguments:

PTR

TGT

PTR shall have the POINTER attribute and it can be of any type.

(Optional) TGT shall be a POINTER or a TARGET. It must have the same type, kind type parameter, and array rank as

PTR.

The status of neither PTR nor TGT can be undefined.

Chapter 6: Intrinsic Procedures 49

Return value:

ASSOCIATED(PTR) returns a scalar value of type LOGICAL(4). There are several cases:

(A) If the optional TGT is not present, then ASSOCIATED(PTR) is true if PTR is associated with a target; otherwise, it returns false.

(B) If TGT is present and a scalar target, the result is true if

TGT is not a 0 sized storage sequence and the target associated with PTR occupies the same storage units. If PTR is disassociated, then the result is false.

TGT and PTR have the same shape, are not 0 sized arrays, are arrays whose elements are not 0 sized storage sequences, and TGT and PTR occupy the same storage units in array element order. As in case(B), the result is false, if PTR is disassociated.

(D) If TGT is present and an scalar pointer, the result is true if target associated with PTR and the target associated with TGT are not 0 sized storage sequences and occupy the same storage units.

The result is false, if either TGT or PTR is disassociated.

(E) If TGT is present and an array pointer, the result is true if target associated with PTR and the target associated with TGT have the same shape, are not 0 sized arrays, are arrays whose elements are not 0 sized storage sequences, and TGT and PTR occupy the same storage units in array element order. The result is false, if either TGT or PTR is disassociated.

Example: program test_associated implicit none real, target :: tgt(2) = (/1., 2./) real, pointer :: ptr(:) ptr => tgt if (associated(ptr) .eqv. .false.) call abort if (associated(ptr,tgt) .eqv. .false.) call abort end program test_associated

See also:

Section 6.162 [NULL], page 128

6.21 ATAN — Arctangent function

Description:

ATAN(X) computes the arctangent of X.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = ATAN(X)

Arguments:

X The type shall be REAL(*).

50 The GNU Fortran Compiler

Return value:

The return value is of type REAL(*) and it lies in the range −π/2 ≤ atan(x) ≤

π/2.

Example: program test_atan real(8) :: x = 2.866_8

x = atan(x) end program test_atan

Specific names:

Name

DATAN(X)

Argument

REAL(8) X

Return type

REAL(8)

See also: Inverse function:

Section 6.206 [TAN], page 153

Standard

F77 and later

6.22 ATAN2 — Arctangent function

Description:

ATAN2(Y,X) computes the arctangent of the complex number X + iY .

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = ATAN2(Y,X)

Arguments:

The type shall be REAL(*).

The type and kind type parameter shall be the same as Y. If

Y is zero, then X must be nonzero.

Return value:

The return value has the same type and kind type parameter as Y. It is the principal value of the complex number X + iY . If X is nonzero, then it lies in the range −π ≤ atan(x) ≤ π. The sign is positive if Y is positive. If Y is zero, then the return value is zero if X is positive and π if X is negative. Finally, if

X is zero, then the magnitude of the result is π/2.

Example: program test_atan2 real(4) :: x = 1.e0_4, y = 0.5e0_4

x = atan2(y,x) end program test_atan2

Specific names:

Name

DATAN2(X)

Argument

REAL(8) X

Return type

REAL(8)

Standard

F77 and later

6.23 ATANH — Hyperbolic arctangent function

Description:

ATANH(X) computes the hyperbolic arctangent of X (inverse of TANH(X)).

Standard : GNU extension

Chapter 6: Intrinsic Procedures 51

Class: Elemental function

Syntax :

RESULT = ATANH(X)

Arguments:

X The type shall be REAL(*) with a magnitude that is less than or equal to one.

Return value:

The return value is of type REAL(*) and it lies in the range −∞ ≤ atanh(x) ≤

∞.

Example:

PROGRAM test_atanh

REAL, DIMENSION(3) :: x = (/ -1.0, 0.0, 1.0 /)

WRITE (*,*) ATANH(x)

END PROGRAM

Specific names:

Name

DATANH(X)

Argument

REAL(8) X

Return type

REAL(8)

See also: Inverse function:

Section 6.207 [TANH], page 153

Standard

GNU extension

6.24 BESJ0 — Bessel function of the first kind of order 0

Description:

BESJ0(X) computes the Bessel function of the first kind of order 0 of X.

Standard : GNU extension

Class:

Syntax :

Elemental function

RESULT = BESJ0(X)

Arguments:

X The type shall be REAL(*), and it shall be scalar.

Return value:

The return value is of type REAL(*) and it lies in the range −0.4027... ≤

Bessel(0, x) ≤ 1.

Example: program test_besj0 real(8) :: x = 0.0_8

x = besj0(x) end program test_besj0

Specific names:

Name

DBESJ0(X)

Argument

REAL(8) X

Return type

REAL(8)

Standard

GNU extension

52 The GNU Fortran Compiler

6.25 BESJ1 — Bessel function of the first kind of order 1

Description:

BESJ1(X) computes the Bessel function of the first kind of order 1 of X.

Standard : GNU extension

Class: Elemental function

Syntax :

RESULT = BESJ1(X)

Arguments:

X The type shall be REAL(*), and it shall be scalar.

Return value:

The return value is of type REAL(*) and it lies in the range −0.5818... ≤

Bessel(0, x) ≤ 0.5818.

Example: program test_besj1 real(8) :: x = 1.0_8

x = besj1(x) end program test_besj1

Specific names:

Name

DBESJ1(X)

Argument

REAL(8) X

Return type

REAL(8)

Standard

GNU extension

6.26 BESJN — Bessel function of the first kind

Description:

BESJN(N, X) computes the Bessel function of the first kind of order N of X.

If both arguments are arrays, their ranks and shapes shall conform.

Standard : GNU extension

Class: Elemental function

Syntax :

RESULT = BESJN(N, X)

Arguments:

Return value:

The return value is a scalar of type REAL(*).

Example:

Shall be a scalar or an array of type INTEGER(*).

Shall be a scalar or an array of type REAL(*).

program test_besjn real(8) :: x = 1.0_8

x = besjn(5,x) end program test_besjn

Specific names:

Name

DBESJN(X)

Argument Return type

INTEGER(*) N REAL(8)

REAL(8) X

Standard

GNU extension

Chapter 6: Intrinsic Procedures

6.27 BESY0 — Bessel function of the second kind of order 0

Description:

BESY0(X) computes the Bessel function of the second kind of order 0 of X.

Standard : GNU extension

Class: Elemental function

Syntax :

RESULT = BESY0(X)

Arguments:

X The type shall be REAL(*), and it shall be scalar.

Return value:

The return value is a scalar of type REAL(*).

Example: program test_besy0 real(8) :: x = 0.0_8

x = besy0(x) end program test_besy0

Specific names:

Name

DBESY0(X)

Argument

REAL(8) X

Return type

REAL(8)

Standard

GNU extension

6.28 BESY1 — Bessel function of the second kind of order 1

Description:

BESY1(X) computes the Bessel function of the second kind of order 1 of X.

Standard : GNU extension

Class:

Syntax :

Elemental function

RESULT = BESY1(X)

Arguments:

X The type shall be REAL(*), and it shall be scalar.

Return value:

The return value is a scalar of type REAL(*).

Example: program test_besy1 real(8) :: x = 1.0_8

x = besy1(x) end program test_besy1

Specific names:

Name

DBESY1(X)

Argument

REAL(8) X

Return type

REAL(8)

Standard

GNU extension

54 The GNU Fortran Compiler

6.29 BESYN — Bessel function of the second kind

Description:

BESYN(N, X) computes the Bessel function of the second kind of order N of X.

If both arguments are arrays, their ranks and shapes shall conform.

Standard : GNU extension

Class:

Syntax :

Elemental function

RESULT = BESYN(N, X)

Arguments:

Shall be a scalar or an array of type INTEGER(*).

Shall be a scalar or an array of type REAL(*).

Return value:

The return value is a scalar of type REAL(*).

Example: program test_besyn real(8) :: x = 1.0_8

x = besyn(5,x) end program test_besyn

Specific names:

Name

DBESYN(N,X)

Argument Return type

INTEGER(*) N REAL(8)

REAL(8) X

Standard

GNU extension

6.30 BIT_SIZE — Bit size inquiry function

Description:

BIT_SIZE(I) returns the number of bits (integer precision plus sign bit) represented by the type of I.

Standard : F95 and later

Class:

Syntax :

Inquiry function

RESULT = BIT_SIZE(I)

Arguments:

I The type shall be INTEGER(*).

Return value:

The return value is of type INTEGER(*)

Example: program test_bit_size integer :: i = 123 integer :: size size = bit_size(i) print *, size end program test_bit_size

Chapter 6: Intrinsic Procedures 55

6.31 BTEST — Bit test function

Description:

BTEST(I,POS) returns logical .TRUE. if the bit at POS in I is set.

Standard : F95 and later

Class:

Syntax :

Elemental function

RESULT = BTEST(I, POS)

Arguments:

POS

The type shall be INTEGER(*).

Return value:

The return value is of type LOGICAL

Example: program test_btest integer :: i = 32768 + 1024 + 64 integer :: pos logical :: bool do pos=0,16 bool = btest(i, pos) print *, pos, bool end do end program test_btest

6.32 C_ASSOCIATED — Status of a C pointer

Description:

C_ASSOICATED(c_prt1[, c_ptr2]) determines the status of the C pointer c ptr1 or if c ptr1 is associated with the target c ptr2.

Standard : F2003 and later

Class:

Syntax :

Inquiry function

RESULT = C_ASSOICATED(c_prt1[, c_ptr2])

Arguments: c ptr1 c ptr2

Return value:

The return value is of type LOGICAL; it is .false. if either c ptr1 is a C NULL pointer or if c ptr1 and c ptr2 point to different addresses.

Example:

Scalar of the type C_PTR or C_FUNPTR.

(Optional) Scalar of the same type as c ptr1.

subroutine association_test(a,b) use iso_c_binding, only: c_associated, c_loc, c_ptr implicit none real, pointer :: a type(c_ptr) :: b if(c_associated(b, c_loc(a))) & stop ’b and a do not point to same target’ end subroutine association_test

56 The GNU Fortran Compiler

See also:

Section 6.36 [C LOC], page 58 ,

Section 6.33 [C FUNLOC], page 56

6.33 C_FUNLOC — Obtain the C address of a procedure

Description:

C_FUNLOC(x) determines the C address of the argument.

Standard : F2003 and later

Class: Inquiry function

Syntax :

RESULT = C_FUNLOC(x)

Arguments: x Interoperable function or pointer to such function.

Return value:

The return value is of type C_FUNPTR and contains the C address of the argument.

Example: module x use iso_c_binding implicit none contains subroutine sub(a) bind(c) real(c_float) :: a a = sqrt(a)+5.0

end subroutine sub end module x program main use iso_c_binding use x implicit none interface subroutine my_routine(p) bind(c,name=’myC_func’) import :: c_funptr type(c_funptr), intent(in) :: p end subroutine end interface call my_routine(c_funloc(sub)) end program main

See also:

Section 6.32 [C ASSOCIATED], page 55 ,

Section 6.36 [C LOC], page 58

Section 6.35 [C F POINTER], page 57 ,

Section 6.34 [C F PROCPOINTER], page 56

6.34 C_F_PROCPOINTER — Convert C into Fortran procedure pointer

Description:

C_F_PROCPOINTER(cptr, fptr) Assign the target of the C function pointer cptr to the Fortran procedure pointer fptr.

Note: Due to the currently lacking support of procedure pointers in GNU Fortran this function is not fully operable.

Chapter 6: Intrinsic Procedures 57

Standard : F2003 and later

Class: Subroutine

Syntax :

Example:

CALL C_F_PROCPOINTER(cptr, fptr)

Arguments: cptr fptr scalar of the type C_FUNPTR. It is INTENT(IN).

procedure pointer interoperable with cptr. It is INTENT(OUT).

program main use iso_c_binding implicit none abstract interface function func(a) import :: c_float real(c_float), intent(in) :: a real(c_float) :: func end function end interface interface function getIterFunc() bind(c,name="getIterFunc") import :: c_funptr type(c_funptr) :: getIterFunc end function end interface type(c_funptr) :: cfunptr procedure(func), pointer :: myFunc cfunptr = getIterFunc() call c_f_procpointer(cfunptr, myFunc) end program main

See also:

Section 6.36 [C LOC], page 58 ,

Section 6.35 [C F POINTER], page 57

6.35 C_F_POINTER — Convert C into Fortran pointer

Description:

C_F_POINTER(cptr, fptr[, shape]) Assign the target the C pointer cptr to the Fortran pointer fptr and specify its shape.

Standard : F2003 and later

Class:

Syntax :

Subroutine

CALL C_F_POINTER(cptr, fptr[, shape])

Arguments: cptr fptr shape scalar of the type C_PTR. It is INTENT(IN).

pointer interoperable with cptr. It is INTENT(OUT).

(Optional) Rank-one array of type INTEGER with INTENT(IN).

It shall be present if and only if fptr is an array. The size must be equal to the rank of fptr.

Example: program main use iso_c_binding

58 The GNU Fortran Compiler implicit none interface subroutine my_routine(p) bind(c,name=’myC_func’) import :: c_ptr type(c_ptr), intent(out) :: p end subroutine end interface type(c_ptr) :: cptr real,pointer :: a(:) call my_routine(cptr) call c_f_pointer(cptr, a, [12]) end program main

See also:

Section 6.36 [C LOC], page 58 ,

Section 6.34 [C F PROCPOINTER], page 56

6.36 C_LOC — Obtain the C address of an object

Description:

C_LOC(x) determines the C address of the argument.

Standard : F2003 and later

Class:

Syntax :

Inquiry function

RESULT = C_LOC(x)

Arguments: x Associated scalar pointer or interoperable scalar or allocated allocatable variable with TARGET attribute.

Return value:

The return value is of type C_PTR and contains the C address of the argument.

Example: subroutine association_test(a,b) use iso_c_binding, only: c_associated, c_loc, c_ptr implicit none real, pointer :: a type(c_ptr) :: b if(c_associated(b, c_loc(a))) & stop ’b and a do not point to same target’ end subroutine association_test

See also:

Section 6.32 [C ASSOCIATED], page 55 ,

Section 6.33 [C FUNLOC], page 56

Section 6.35 [C F POINTER], page 57 ,

Section 6.34 [C F PROCPOINTER], page 56

6.37 CEILING — Integer ceiling function

Description:

CEILING(X) returns the least integer greater than or equal to X.

Standard : F95 and later

Class:

Syntax :

Elemental function

RESULT = CEILING(X [, KIND])

Chapter 6: Intrinsic Procedures 59

Arguments:

KIND

The type shall be REAL(*).

(Optional) An INTEGER(*) initialization expression indicating the kind parameter of the result.

Return value:

The return value is of type INTEGER(KIND)

Example: program test_ceiling real :: x = 63.29

real :: y = -63.59

print *, ceiling(x) ! returns 64 print *, ceiling(y) ! returns -63 end program test_ceiling

See also:

Section 6.73 [FLOOR], page 81

Section 6.160 [NINT], page 127

6.38 CHAR — Character conversion function

Description:

CHAR(I [, KIND]) returns the character represented by the integer I.

Standard : F77 and later

Class:

Syntax :

Elemental function

RESULT = CHAR(I [, KIND])

Arguments:

KIND

The type shall be INTEGER(*).

(Optional) An INTEGER(*) initialization expression indicating the kind parameter of the result.

Return value:

The return value is of type CHARACTER(1)

Example: program test_char integer :: i = 74 character(1) :: c c = char(i) print *, i, c ! returns ’J’ end program test_char

Note: See

Section 6.104 [ICHAR], page 97

for a discussion of converting between numerical values and formatted string representations.

See also:

Section 6.5 [ACHAR], page 39

Section 6.98 [IACHAR], page 94 ,

Section 6.104

[ICHAR], page 97

6.39 CHDIR — Change working directory

Description:

Change current working directory to a specified path.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

60 The GNU Fortran Compiler

Standard : GNU extension

Class:

Syntax :

Subroutine, function

CALL CHDIR(NAME [, STATUS])

STATUS = CHDIR(NAME)

Arguments:

NAME

STATUS

The type shall be CHARACTER(*) and shall specify a valid path within the file system.

(Optional) INTEGER status flag of the default kind. Returns

0 on success, and a system specific and nonzero error code otherwise.

Example:

PROGRAM test_chdir

CHARACTER(len=255) :: path

CALL getcwd(path)

WRITE(*,*) TRIM(path)

CALL chdir("/tmp")

CALL getcwd(path)

WRITE(*,*) TRIM(path)

END PROGRAM

See also:

Section 6.88 [GETCWD], page 90

6.40 CHMOD — Change access permissions of files

Description:

CHMOD changes the permissions of a file. This function invokes /bin/chmod and might therefore not work on all platforms.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL CHMOD(NAME, MODE[, STATUS])

STATUS = CHMOD(NAME, MODE)

Arguments:

NAME Scalar CHARACTER with the file name. Trailing blanks are ignored unless the character achar(0) is present, then all characters up to and excluding achar(0) are used as the file name.

MODE

STATUS

Scalar CHARACTER giving the file permission. MODE uses the same syntax as the MODE argument of /bin/chmod.

(optional) scalar INTEGER, which is 0 on success and nonzero otherwise.

Chapter 6: Intrinsic Procedures 61

Return value:

In either syntax, STATUS is set to 0 on success and nonzero otherwise.

Example:

CHMOD as subroutine program chmod_test implicit none integer :: status call chmod(’test.dat’,’u+x’,status) print *, ’Status: ’, status end program chmod_test

CHMOD as function: program chmod_test implicit none integer :: status status = chmod(’test.dat’,’u+x’) print *, ’Status: ’, status end program chmod_test

6.41 CMPLX — Complex conversion function

Description:

CMPLX(X [, Y [, KIND]]) returns a complex number where X is converted to the real component. If Y is present it is converted to the imaginary component.

If Y is not present then the imaginary component is set to 0.0. If X is complex then Y must not be present.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = CMPLX(X [, Y [, KIND]])

Arguments:

KIND

The type may be INTEGER(*), REAL(*), or COMPLEX(*).

(Optional; only allowed if X is not COMPLEX(*).) May be

INTEGER(*) or REAL(*).

(Optional) An INTEGER(*) initialization expression indicating the kind parameter of the result.

Return value:

The return value is of COMPLEX type, with a kind equal to KIND if it is specified.

If KIND is not specified, the result is of the default COMPLEX kind, regardless of the kinds of X and Y.

Example: program test_cmplx integer :: i = 42 real :: x = 3.14

complex :: z z = cmplx(i, x) print *, z, cmplx(x) end program test_cmplx

See also:

Section 6.43 [COMPLEX], page 62

62 The GNU Fortran Compiler

6.42 COMMAND_ARGUMENT_COUNT — Get number of command line arguments

Description:

COMMAND_ARGUMENT_COUNT() returns the number of arguments passed on the command line when the containing program was invoked.

Standard : F2003

Class: Inquiry function

Syntax :

RESULT = COMMAND_ARGUMENT_COUNT()

Arguments:

None

Return value:

The return value is of type INTEGER(4)

Example: program test_command_argument_count integer :: count count = command_argument_count() print *, count end program test_command_argument_count

See also:

Section 6.86 [GET COMMAND], page 89

Section 6.87 [GET COMMAND ARGUMENT], page 89

6.43 COMPLEX — Complex conversion function

Description:

COMPLEX(X, Y) returns a complex number where X is converted to the real component and Y is converted to the imaginary component.

Standard : GNU extension

Class:

Syntax :

Elemental function

RESULT = COMPLEX(X, Y)

Arguments:

The type may be INTEGER(*) or REAL(*).

Return value:

If X and Y are both of INTEGER type, then the return value is of default COMPLEX type.

If X and Y are of REAL type, or one is of REAL type and one is of INTEGER type, then the return value is of COMPLEX type with a kind equal to that of the REAL argument with the highest precision.

Example: program test_complex integer :: i = 42 real :: x = 3.14

print *, complex(i, x) end program test_complex

Chapter 6: Intrinsic Procedures 63

See also:

Section 6.41 [CMPLX], page 61

6.44 CONJG — Complex conjugate function

Description:

CONJG(Z) returns the conjugate of Z. If Z is (x, y) then the result is (x, -y)

Standard : F77 and later, has overloads that are GNU extensions

Class:

Syntax :

Elemental function

Z = CONJG(Z)

Arguments:

Z The type shall be COMPLEX(*).

Return value:

The return value is of type COMPLEX(*).

Example: program test_conjg complex :: z = (2.0, 3.0) complex(8) :: dz = (2.71_8, -3.14_8) z= conjg(z) print *, z dz = dconjg(dz) print *, dz end program test_conjg

Specific names:

Name

DCONJG(Z)

Argument

COMPLEX(8) Z

Return type

COMPLEX(8)

Standard

GNU extension

6.45 COS — Cosine function

Description:

COS(X) computes the cosine of X.

Standard : F77 and later, has overloads that are GNU extensions

Class: Elemental function

Syntax :

RESULT = COS(X)

Arguments:

X The type shall be REAL(*) or COMPLEX(*).

Return value:

The return value is of type REAL(*) and it lies in the range −1 ≤ cos(x) ≤ 1.

The kind type parameter is the same as X.

Example: program test_cos real :: x = 0.0

x = cos(x) end program test_cos

64 The GNU Fortran Compiler

Specific names:

Name

DCOS(X)

CCOS(X)

ZCOS(X)

CDCOS(X)

Argument

REAL(8) X

COMPLEX(4) X

Return type

REAL(8)

COMPLEX(4)

COMPLEX(8) X COMPLEX(8)

See also: Inverse function:

Section 6.6 [ACOS], page 40

Standard

F77 and later

GNU extension

6.46 COSH — Hyperbolic cosine function

Description:

COSH(X) computes the hyperbolic cosine of X.

Standard : F77 and later

Class:

Syntax :

Elemental function

X = COSH(X)

Arguments:

X The type shall be REAL(*).

Return value:

The return value is of type REAL(*) and it is positive (cosh(x) ≥ 0.

Example: program test_cosh real(8) :: x = 1.0_8

x = cosh(x) end program test_cosh

Specific names:

Name

DCOSH(X)

Argument

REAL(8) X

Return type

REAL(8)

See also: Inverse function:

Section 6.7 [ACOSH], page 40

Standard

F77 and later

6.47 COUNT — Count function

Description:

COUNT(MASK [, DIM [, KIND]]) counts the number of .TRUE. elements of

MASK along the dimension of DIM. If DIM is omitted it is taken to be 1.

DIM is a scaler of type INTEGER in the range of 1/leqDIM/leqn) where n is the rank of MASK.

Standard : F95 and later

Class: Transformational function

Syntax :

RESULT = COUNT(MASK [, DIM [, KIND]])

Arguments:

MASK

DIM

KIND

The type shall be LOGICAL.

(Optional) The type shall be INTEGER.

(Optional) An INTEGER initialization expression indicating the kind parameter of the result.

Chapter 6: Intrinsic Procedures 65

Return value:

The return value is of type INTEGER and of kind KIND. If KIND is absent, the return value is of default integer kind. The result has a rank equal to that of

MASK.

Example: program test_count integer, dimension(2,3) :: a, b logical, dimension(2,3) :: mask a = reshape( (/ 1, 2, 3, 4, 5, 6 /), (/ 2, 3 /)) b = reshape( (/ 0, 7, 3, 4, 5, 8 /), (/ 2, 3 /)) print ’(3i3)’, a(1,:) print ’(3i3)’, a(2,:) print * print ’(3i3)’, b(1,:) print ’(3i3)’, b(2,:) print * mask = a.ne.b

print ’(3l3)’, mask(1,:) print ’(3l3)’, mask(2,:) print * print ’(3i3)’, count(mask) print * print ’(3i3)’, count(mask, 1) print * print ’(3i3)’, count(mask, 2) end program test_count

6.48 CPU_TIME — CPU elapsed time in seconds

Description:

Returns a REAL(*) value representing the elapsed CPU time in seconds. This is useful for testing segments of code to determine execution time.

If a time source is available, time will be reported with microsecond resolution.

If no time source is available, TIME is set to -1.0.

Note that TIME may contain a, system dependent, arbitrary offset and may not start with 0.0. For CPU_TIME, the absolute value is meaningless, only differences between subsequent calls to this subroutine, as shown in the example below, should be used.

Standard : F95 and later

Class: Subroutine

Syntax :

CALL CPU_TIME(TIME)

Arguments:

TIME The type shall be REAL(*) with INTENT(OUT).

Return value:

None

Example: program test_cpu_time real :: start, finish

66 The GNU Fortran Compiler call cpu_time(start)

! put code to test here call cpu_time(finish) print ’("Time = ",f6.3," seconds.")’,finish-start end program test_cpu_time

Section 6.51 [DATE AND TIME], page 67

6.49 CSHIFT — Circular shift elements of an array

Description:

CSHIFT(ARRAY, SHIFT [, DIM]) performs a circular shift on elements of AR-

RAY along the dimension of DIM. If DIM is omitted it is taken to be 1. DIM is a scaler of type INTEGER in the range of 1/leqDIM/leqn) where n is the rank of ARRAY. If the rank of ARRAY is one, then all elements of ARRAY are shifted by SHIFT places. If rank is greater than one, then all complete rank one sections of ARRAY along the given dimension are shifted. Elements shifted out one end of each rank one section are shifted back in the other end.

Standard : F95 and later

Class: Transformational function

Syntax :

RESULT = CSHIFT(ARRAY, SHIFT [, DIM])

Arguments:

ARRAY

SHIFT

DIM

Shall be an array of any type.

The type shall be INTEGER.

Return value:

Returns an array of same type and rank as the ARRAY argument.

Example: program test_cshift integer, dimension(3,3) :: a a = reshape( (/ 1, 2, 3, 4, 5, 6, 7, 8, 9 /), (/ 3, 3 /)) print ’(3i3)’, a(1,:) print ’(3i3)’, a(2,:) print ’(3i3)’, a(3,:) a = cshift(a, SHIFT=(/1, 2, -1/), DIM=2) print * print ’(3i3)’, a(1,:) print ’(3i3)’, a(2,:) print ’(3i3)’, a(3,:) end program test_cshift

6.50 CTIME — Convert a time into a string

Description:

CTIME converts a system time value, such as returned by TIME8(), to a string of the form ‘Sat Aug 19 18:13:14 1995’.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Chapter 6: Intrinsic Procedures 67

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL CTIME(TIME, RESULT).

RESULT = CTIME(TIME), (not recommended).

Arguments:

TIME

RESULT

The type shall be of type INTEGER(KIND=8).

The type shall be of type CHARACTER.

Return value:

The converted date and time as a string.

Example: program test_ctime integer(8) :: i character(len=30) :: date i = time8()

! Do something, main part of the program call ctime(i,date) print *, ’Program was started on ’, date end program test_ctime

6.51 DATE_AND_TIME — Date and time subroutine

Description:

DATE_AND_TIME(DATE, TIME, ZONE, VALUES) gets the corresponding date and time information from the real-time system clock. DATE is INTENT(OUT) and has form ccyymmdd. TIME is INTENT(OUT) and has form hhmmss.sss. ZONE is INTENT(OUT) and has form (+-)hhmm, representing the difference with respect to Coordinated Universal Time (UTC). Unavailable time and date parameters return blanks.

VALUES is INTENT(OUT) and provides the following:

VALUE(1):

VALUE(2):

VALUE(3):

VALUE(4):

VALUE(5):

VALUE(6):

VALUE(7):

VALUE(8):

The year

The month

The day of the month

Time difference with UTC in minutes

The hour of the day

The minutes of the hour

The seconds of the minute

The milliseconds of the second

Standard : F95 and later

Class: Subroutine

68 The GNU Fortran Compiler

Syntax :

CALL DATE_AND_TIME([DATE, TIME, ZONE, VALUES])

Arguments:

DATE

TIME

ZONE

VALUES

(Optional) The type shall be CHARACTER(8) or larger.

(Optional) The type shall be CHARACTER(10) or larger.

(Optional) The type shall be CHARACTER(5) or larger.

(Optional) The type shall be INTEGER(8).

Return value:

None

Example: program test_time_and_date character(8) :: date character(10) :: time character(5) :: zone integer,dimension(8) :: values

! using keyword arguments call date_and_time(date,time,zone,values) call date_and_time(DATE=date,ZONE=zone) call date_and_time(TIME=time) call date_and_time(VALUES=values) print ’(a,2x,a,2x,a)’, date, time, zone print ’(8i5))’, values end program test_time_and_date

See also:

Section 6.48 [CPU TIME], page 65 ,

Section 6.205 [SYSTEM CLOCK], page 152

6.52 DBLE — Double conversion function

Description:

DBLE(X) Converts X to double precision real type.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = DBLE(X)

Arguments:

X The type shall be INTEGER(*), REAL(*), or COMPLEX(*).

Return value:

The return value is of type double precision real.

Example: program test_dble real :: x = 2.18

integer :: i = 5 complex :: z = (2.3,1.14) print *, dble(x), dble(i), dble(z) end program test_dble

See also:

Section 6.54 [DFLOAT], page 69 ,

Section 6.70 [FLOAT], page 79 ,

Section 6.175

[REAL], page 135

Chapter 6: Intrinsic Procedures 69

6.53 DCMPLX — Double complex conversion function

Description:

DCMPLX(X [,Y]) returns a double complex number where X is converted to the real component. If Y is present it is converted to the imaginary component. If

Y is not present then the imaginary component is set to 0.0. If X is complex then Y must not be present.

Standard : GNU extension

Class: Elemental function

Syntax :

RESULT = DCMPLX(X [, Y])

Arguments:

The type may be INTEGER(*), REAL(*), or COMPLEX(*).

(Optional if X is not COMPLEX(*).) May be INTEGER(*) or

REAL(*).

Return value:

The return value is of type COMPLEX(8)

Example: program test_dcmplx integer :: i = 42 real :: x = 3.14

complex :: z z = cmplx(i, x) print *, dcmplx(i) print *, dcmplx(x) print *, dcmplx(z) print *, dcmplx(x,i) end program test_dcmplx

6.54 DFLOAT — Double conversion function

Description:

DFLOAT(X) Converts X to double precision real type.

Standard : GNU extension

Class: Elemental function

Syntax :

RESULT = DFLOAT(X)

Arguments:

X The type shall be INTEGER(*).

Return value:

The return value is of type double precision real.

Example: program test_dfloat integer :: i = 5 print *, dfloat(i) end program test_dfloat

See also:

Section 6.70 [FLOAT], page 79 ,

Section 6.175

[REAL], page 135

70 The GNU Fortran Compiler

6.55 DIGITS — Significant digits function

Description:

DIGITS(X) returns the number of significant digits of the internal model representation of X. For example, on a system using a 32-bit floating point representation, a default real number would likely return 24.

Standard : F95 and later

Class:

Syntax :

Inquiry function

RESULT = DIGITS(X)

Arguments:

X The type may be INTEGER(*) or REAL(*).

Return value:

The return value is of type INTEGER.

Example: program test_digits integer :: i = 12345 real :: x = 3.143

real(8) :: y = 2.33

print *, digits(i) print *, digits(x) print *, digits(y) end program test_digits

6.56 DIM — Positive difference

Description:

DIM(X,Y) returns the difference X-Y if the result is positive; otherwise returns zero.

Standard : F77 and later

Class:

Syntax :

Arguments:

Elemental function

RESULT = DIM(X, Y)

The type shall be INTEGER(*) or REAL(*)

The type shall be the same type and kind as X.

Return value:

The return value is of type INTEGER(*) or REAL(*).

Example: program test_dim integer :: i real(8) :: x i = dim(4, 15) x = dim(4.345_8, 2.111_8) print *, i print *, x end program test_dim

Chapter 6: Intrinsic Procedures 71

Specific names:

Name

IDIM(X,Y)

DDIM(X,Y)

Argument

INTEGER(4)

X,Y

REAL(8) X,Y

Return type

INTEGER(4)

REAL(8)

Standard

F77 and later

6.57 DOT_PRODUCT — Dot product function

Description:

DOT_PRODUCT(X,Y) computes the dot product multiplication of two vectors X and Y. The two vectors may be either numeric or logical and must be arrays of rank one and of equal size. If the vectors are INTEGER(*) or REAL(*), the result is SUM(X*Y). If the vectors are COMPLEX(*), the result is SUM(CONJG(X)*Y). If the vectors are LOGICAL, the result is ANY(X.AND.Y).

Standard : F95 and later

Class:

Syntax :

Transformational function

RESULT = DOT_PRODUCT(X, Y)

Arguments:

The type shall be numeric or LOGICAL, rank 1.

Return value:

If the arguments are numeric, the return value is a scaler of numeric type,

INTEGER(*), REAL(*), or COMPLEX(*). If the arguments are LOGICAL, the return value is .TRUE. or .FALSE..

Example: program test_dot_prod integer, dimension(3) :: a, b a = (/ 1, 2, 3 /) b = (/ 4, 5, 6 /) print ’(3i3)’, a print * print ’(3i3)’, b print * print *, dot_product(a,b) end program test_dot_prod

6.58 DPROD — Double product function

Description:

DPROD(X,Y) returns the product X*Y.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = DPROD(X, Y)

Arguments:

The type shall be REAL.

72 The GNU Fortran Compiler

Return value:

The return value is of type REAL(8).

Example: program test_dprod real :: x = 5.2

real :: y = 2.3

real(8) :: d d = dprod(x,y) print *, d end program test_dprod

6.59 DREAL — Double real part function

Description:

DREAL(Z) returns the real part of complex variable Z.

Standard : GNU extension

Class: Elemental function

Syntax :

RESULT = DREAL(Z)

Arguments:

Z The type shall be COMPLEX(8).

Return value:

The return value is of type REAL(8).

Example: program test_dreal complex(8) :: z = (1.3_8,7.2_8) print *, dreal(z) end program test_dreal

See also:

Section 6.10 [AIMAG], page 42

6.60 DTIME — Execution time subroutine (or function)

Description:

DTIME(TARRAY, RESULT) initially returns the number of seconds of runtime since the start of the process’s execution in RESULT. TARRAY returns the user and system components of this time in TARRAY(1) and TARRAY(2) respectively.

RESULT is equal to TARRAY(1) + TARRAY(2).

Subsequent invocations of DTIME return values accumulated since the previous invocation.

On some systems, the underlying timings are represented using types with sufficiently small limits that overflows (wrap around) are possible, such as 32bit types. Therefore, the values returned by this intrinsic might be, or become, negative, or numerically less than previous values, during a single run of the compiled program.

Please note, that this implementation is thread safe if used within OpenMP directives, i. e. its state will be consistent while called from multiple threads.

Chapter 6: Intrinsic Procedures 73

Standard : GNU extension

Class: Subroutine, function

Syntax :

However, if DTIME is called from multiple threads, the result is still the time since the last invocation. This may not give the intended results. If possible, use CPU_TIME instead.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

TARRAY and RESULT are INTENT(OUT) and provide the following:

TARRAY(1):

TARRAY(2):

RESULT:

User time in seconds.

System time in seconds.

Run time since start in seconds.

CALL DTIME(TARRAY, RESULT).

RESULT = DTIME(TARRAY), (not recommended).

Arguments:

TARRAY

RESULT

The type shall be REAL, DIMENSION(2).

The type shall be REAL.

Return value:

Elapsed time in seconds since the last invocation or since the start of program execution if not called before.

Example: program test_dtime integer(8) :: i, j real, dimension(2) :: tarray real :: result call dtime(tarray, result) print *, result print *, tarray(1) print *, tarray(2) do i=1,100000000 j = i * i - i

! Just a delay end do call dtime(tarray, result) print *, result print *, tarray(1) print *, tarray(2) end program test_dtime

See also:

6.61 EOSHIFT — End-off shift elements of an array

Description:

EOSHIFT(ARRAY, SHIFT[,BOUNDARY, DIM]) performs an end-off shift on elements of ARRAY along the dimension of DIM. If DIM is omitted it is taken to be 1. DIM is a scaler of type INTEGER in the range of 1/leqDIM/leqn) where n is the rank of ARRAY. If the rank of ARRAY is one, then all elements of

74 The GNU Fortran Compiler

ARRAY are shifted by SHIFT places. If rank is greater than one, then all complete rank one sections of ARRAY along the given dimension are shifted.

Elements shifted out one end of each rank one section are dropped. If BOUND-

ARY is present then the corresponding value of from BOUNDARY is copied back in the other end. If BOUNDARY is not present then the following are copied in depending on the type of ARRAY.

Array Type

Numeric

Boundary Value

0 of the type and kind of ARRAY.

Logical

.FALSE..

Character(len) len blanks.

Standard : F95 and later

Class:

Syntax :

Transformational function

RESULT = EOSHIFT(ARRAY, SHIFT [, BOUNDARY, DIM])

Arguments:

ARRAY

SHIFT

May be any type, not scaler.

The type shall be INTEGER.

BOUNDARY Same type as ARRAY.

DIM The type shall be INTEGER.

Return value:

Returns an array of same type and rank as the ARRAY argument.

Example: program test_eoshift integer, dimension(3,3) :: a a = reshape( (/ 1, 2, 3, 4, 5, 6, 7, 8, 9 /), (/ 3, 3 /)) print ’(3i3)’, a(1,:) print ’(3i3)’, a(2,:) print ’(3i3)’, a(3,:) a = EOSHIFT(a, SHIFT=(/1, 2, 1/), BOUNDARY=-5, DIM=2) print * print ’(3i3)’, a(1,:) print ’(3i3)’, a(2,:) print ’(3i3)’, a(3,:) end program test_eoshift

6.62 EPSILON — Epsilon function

Description:

EPSILON(X) returns a nearly negligible number relative to 1.

Standard : F95 and later

Class:

Syntax :

Inquiry function

RESULT = EPSILON(X)

Arguments:

X The type shall be REAL(*).

Return value:

The return value is of same type as the argument.

Chapter 6: Intrinsic Procedures 75

Example: program test_epsilon real :: x = 3.143

real(8) :: y = 2.33

print *, EPSILON(x) print *, EPSILON(y) end program test_epsilon

6.63 ERF — Error function

Description:

ERF(X) computes the error function of X.

Standard : GNU Extension

Class:

Syntax :

Elemental function

RESULT = ERF(X)

Arguments:

X The type shall be REAL(*), and it shall be scalar.

Return value:

The return value is a scalar of type REAL(*) and it is positive (−1 ≤ erf (x) ≤ 1.

Example: program test_erf real(8) :: x = 0.17_8

x = erf(x) end program test_erf

Specific names:

Name

DERF(X)

Argument

REAL(8) X

Return type

REAL(8)

Standard

GNU extension

6.64 ERFC — Error function

Description:

ERFC(X) computes the complementary error function of X.

Standard : GNU extension

Class: Elemental function

Syntax :

RESULT = ERFC(X)

Arguments:

X The type shall be REAL(*), and it shall be scalar.

Return value:

The return value is a scalar of type REAL(*) and it is positive (0 ≤ erf c(x) ≤ 2.

Example: program test_erfc real(8) :: x = 0.17_8

x = erfc(x) end program test_erfc

76 The GNU Fortran Compiler

Specific names:

Name

DERFC(X)

Argument

REAL(8) X

Return type

REAL(8)

Standard

GNU extension

6.65 ETIME — Execution time subroutine (or function)

Description:

ETIME(TARRAY, RESULT) returns the number of seconds of runtime since the start of the process’s execution in RESULT. TARRAY returns the user and system components of this time in TARRAY(1) and TARRAY(2) respectively. RE-

SULT is equal to TARRAY(1) + TARRAY(2).

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

TARRAY and RESULT are INTENT(OUT) and provide the following:

TARRAY(1):

TARRAY(2):

RESULT:

User time in seconds.

System time in seconds.

Run time since start in seconds.

Standard : GNU extension

Class:

Syntax :

Subroutine, function

CALL ETIME(TARRAY, RESULT).

RESULT = ETIME(TARRAY), (not recommended).

Arguments:

TARRAY

RESULT

The type shall be REAL, DIMENSION(2).

The type shall be REAL.

Return value:

Elapsed time in seconds since the start of program execution.

Example: program test_etime integer(8) :: i, j real, dimension(2) :: tarray real :: result call ETIME(tarray, result) print *, result print *, tarray(1) print *, tarray(2) do i=1,100000000 j = i * i - i

! Just a delay end do call ETIME(tarray, result) print *, result

Chapter 6: Intrinsic Procedures 77 print *, tarray(1) print *, tarray(2) end program test_etime

See also:

Section 6.2 [ABORT], page 37 ,

6.66 EXIT — Exit the program with status.

Description:

EXIT causes immediate termination of the program with status. If status is omitted it returns the canonical success for the system. All Fortran I/O units are closed.

Standard : GNU extension

Class: Subroutine

Syntax :

CALL EXIT([STATUS])

Arguments:

STATUS Shall be an INTEGER of the default kind.

Return value:

STATUS is passed to the parent process on exit.

Example: program test_exit integer :: STATUS = 0 print *, ’This program is going to exit.’ call EXIT(STATUS) end program test_exit

See also:

Section 6.121 [KILL], page 106

6.67 EXP — Exponential function

Description:

EXP(X) computes the base e exponential of X.

Standard : F77 and later, has overloads that are GNU extensions

Class:

Syntax :

Arguments:

Elemental function

RESULT = EXP(X)

The type shall be REAL(*) or COMPLEX(*).

Return value:

The return value has same type and kind as X.

Example: program test_exp real :: x = 1.0

x = exp(x) end program test_exp

78 The GNU Fortran Compiler

Specific names:

Name

DEXP(X)

CEXP(X)

ZEXP(X)

CDEXP(X)

Argument

REAL(8) X

Return type

REAL(8)

COMPLEX(4) X COMPLEX(4)

COMPLEX(8) X COMPLEX(8)

Standard

F77 and later

GNU extension

6.68 EXPONENT — Exponent function

Description:

EXPONENT(X) returns the value of the exponent part of X. If X is zero the value returned is zero.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = EXPONENT(X)

Arguments:

X The type shall be REAL(*).

Return value:

The return value is of type default INTEGER.

Example: program test_exponent real :: x = 1.0

integer :: i i = exponent(x) print *, i print *, exponent(0.0) end program test_exponent

6.69 FDATE — Get the current time as a string

Description:

FDATE(DATE) returns the current date (using the same format as CTIME) in

DATE. It is equivalent to CALL CTIME(DATE, TIME()).

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

DATE is an INTENT(OUT) CHARACTER variable.

Standard : GNU extension

Class:

Syntax :

Subroutine, function

CALL FDATE(DATE).

DATE = FDATE(), (not recommended).

Arguments:

DATE The type shall be of type CHARACTER.

Chapter 6: Intrinsic Procedures 79

Return value:

The current date as a string.

Example: program test_fdate integer(8) :: i, j character(len=30) :: date call fdate(date) print *, ’Program started on ’, date do i = 1, 100000000 ! Just a delay j = i * i - i end do call fdate(date) print *, ’Program ended on ’, date end program test_fdate

6.70 FLOAT — Convert integer to default real

Description:

FLOAT(I) converts the integer I to a default real value.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = FLOAT(I)

Arguments:

I The type shall be INTEGER(*).

Return value:

The return value is of type default REAL.

Example: program test_float integer :: i = 1 if (float(i) /= 1.) call abort end program test_float

See also:

Section 6.54 [DFLOAT], page 69

Section 6.175

[REAL], page 135

6.71 FGET — Read a single character in stream mode from stdin

Description:

Read a single character in stream mode from stdin by bypassing normal formatted output. Stream I/O should not be mixed with normal record-oriented

(formatted or unformatted) I/O on the same unit; the results are unpredictable.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Note that the FGET intrinsic is provided for backwards compatibility with g77.

GNU Fortran provides the Fortran 2003 Stream facility. Programmers should consider the use of new stream IO feature in new code for future portability.

80 The GNU Fortran Compiler

Standard : GNU extension

Class:

Syntax :

Subroutine, function

CALL FGET(C [, STATUS])

Arguments:

STATUS

The type shall be CHARACTER.

(Optional) status flag of type INTEGER. Returns 0 on success,

-1 on end-of-file, and a system specific positive error code otherwise.

Example:

PROGRAM test_fget

INTEGER, PARAMETER :: strlen = 100

INTEGER :: status, i = 1

CHARACTER(len=strlen) :: str = ""

WRITE (*,*) ’Enter text:’

CALL fget(str(i:i), status) if (status /= 0 .OR. i > strlen) exit i = i + 1

END DO

WRITE (*,*) TRIM(str)

END PROGRAM

See also:

Section 6.72 [FGETC], page 80 ,

Section 6.76 [FPUT], page 82 ,

Section 6.77

[FPUTC], page 83

6.72 FGETC — Read a single character in stream mode

Description:

Read a single character in stream mode by bypassing normal formatted output.

Stream I/O should not be mixed with normal record-oriented (formatted or unformatted) I/O on the same unit; the results are unpredictable.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Note that the FGET intrinsic is provided for backwards compatibility with g77.

GNU Fortran provides the Fortran 2003 Stream facility. Programmers should consider the use of new stream IO feature in new code for future portability.

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL FGETC(UNIT, C [, STATUS])

Arguments:

UNIT

STATUS

The type shall be INTEGER.

The type shall be CHARACTER.

(Optional) status flag of type INTEGER. Returns 0 on success, -1 on end-of-file and a system specific positive error code otherwise.

Chapter 6: Intrinsic Procedures 81

Example:

PROGRAM test_fgetc

INTEGER :: fd = 42, status

CHARACTER :: c

OPEN(UNIT=fd, FILE="/etc/passwd", ACTION="READ", STATUS = "OLD")

CALL fgetc(fd, c, status)

IF (status /= 0) EXIT call fput(c)

END DO

CLOSE(UNIT=fd)

END PROGRAM

See also:

Section 6.71 [FGET], page 79 ,

Section 6.76 [FPUT], page 82 ,

Section 6.77

[FPUTC], page 83

6.73 FLOOR — Integer floor function

Description:

FLOOR(X) returns the greatest integer less than or equal to X.

Standard : F95 and later

Class:

Syntax :

Elemental function

RESULT = FLOOR(X [, KIND])

Arguments:

KIND

The type shall be REAL(*).

(Optional) An INTEGER(*) initialization expression indicating the kind parameter of the result.

Return value:

The return value is of type INTEGER(KIND)

Example: program test_floor real :: x = 63.29

real :: y = -63.59

print *, floor(x) ! returns 63 print *, floor(y) ! returns -64 end program test_floor

See also:

Section 6.37 [CEILING], page 58 ,

Section 6.160 [NINT], page 127

6.74 FLUSH — Flush I/O unit(s)

Description:

Flushes Fortran unit(s) currently open for output. Without the optional argument, all units are flushed, otherwise just the unit specified.

Standard : GNU extension

Class:

Syntax :

Subroutine

CALL FLUSH(UNIT)

82 The GNU Fortran Compiler

Arguments:

Note:

UNIT (Optional) The type shall be INTEGER.

Beginning with the Fortran 2003 standard, there is a FLUSH statement that should be preferred over the FLUSH intrinsic.

6.75 FNUM — File number function

Description:

FNUM(UNIT) returns the POSIX file descriptor number corresponding to the open Fortran I/O unit UNIT.

Standard : GNU extension

Class:

Syntax :

Function

RESULT = FNUM(UNIT)

Arguments:

UNIT The type shall be INTEGER.

Return value:

The return value is of type INTEGER

Example: program test_fnum integer :: i open (unit=10, status = "scratch") i = fnum(10) print *, i close (10) end program test_fnum

6.76 FPUT — Write a single character in stream mode to stdout

Description:

Write a single character in stream mode to stdout by bypassing normal formatted output. Stream I/O should not be mixed with normal record-oriented

(formatted or unformatted) I/O on the same unit; the results are unpredictable.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Note that the FGET intrinsic is provided for backwards compatibility with g77.

GNU Fortran provides the Fortran 2003 Stream facility. Programmers should consider the use of new stream IO feature in new code for future portability.

Standard : GNU extension

Class:

Syntax :

Subroutine, function

CALL FPUT(C [, STATUS])

Chapter 6: Intrinsic Procedures 83

Arguments:

STATUS

The type shall be CHARACTER.

(Optional) status flag of type INTEGER. Returns 0 on success, -1 on end-of-file and a system specific positive error code otherwise.

Example:

PROGRAM test_fput

CHARACTER(len=10) :: str = "gfortran"

INTEGER :: i

DO i = 1, len_trim(str)

CALL fput(str(i:i))

END DO

END PROGRAM

See also:

Section 6.77 [FPUTC], page 83 ,

Section 6.71 [FGET], page 79 ,

Section 6.72

[FGETC], page 80

6.77 FPUTC — Write a single character in stream mode

Description:

Write a single character in stream mode by bypassing normal formatted output.

Stream I/O should not be mixed with normal record-oriented (formatted or unformatted) I/O on the same unit; the results are unpredictable.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Note that the FGET intrinsic is provided for backwards compatibility with g77.

GNU Fortran provides the Fortran 2003 Stream facility. Programmers should consider the use of new stream IO feature in new code for future portability.

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL FPUTC(UNIT, C [, STATUS])

Arguments:

UNIT

STATUS

The type shall be INTEGER.

The type shall be CHARACTER.

(Optional) status flag of type INTEGER. Returns 0 on success, -1 on end-of-file and a system specific positive error code otherwise.

Example:

PROGRAM test_fputc

CHARACTER(len=10) :: str = "gfortran"

INTEGER :: fd = 42, i

OPEN(UNIT = fd, FILE = "out", ACTION = "WRITE", STATUS="NEW")

DO i = 1, len_trim(str)

CALL fputc(fd, str(i:i))

END DO

84 The GNU Fortran Compiler

CLOSE(fd)

END PROGRAM

See also:

Section 6.76 [FPUT], page 82 ,

Section 6.71 [FGET], page 79 ,

Section 6.72

[FGETC], page 80

6.78 FRACTION — Fractional part of the model representation

Description:

FRACTION(X) returns the fractional part of the model representation of X.

Standard : F95 and later

Class: Elemental function

Syntax :

Y = FRACTION(X)

Arguments:

X The type of the argument shall be a REAL.

Return value:

The return value is of the same type and kind as the argument. The fractional part of the model representation of X is returned; it is X * RADIX(X)**(-

EXPONENT(X)).

Example: program test_fraction real :: x x = 178.1387e-4 print *, fraction(x), x * radix(x)**(-exponent(x)) end program test_fraction

6.79 FREE — Frees memory

Description:

Frees memory previously allocated by MALLOC(). The FREE intrinsic is an extension intended to be used with Cray pointers, and is provided in GNU Fortran to allow user to compile legacy code. For new code using Fortran 95 pointers, the memory de-allocation intrinsic is DEALLOCATE.

Standard : GNU extension

Class:

Syntax :

Subroutine

CALL FREE(PTR)

Arguments:

PTR The type shall be INTEGER. It represents the location of the memory that should be de-allocated.

Return value:

None

Example: See MALLOC for an example.

See also:

Section 6.141 [MALLOC], page 116

Chapter 6: Intrinsic Procedures 85

6.80 FSEEK — Low level file positioning subroutine

Description:

Moves UNIT to the specified OFFSET. If WHENCE is set to 0, the OFFSET is taken as an absolute value SEEK_SET, if set to 1, OFFSET is taken to be relative to the current position SEEK_CUR, and if set to 2 relative to the end of the file SEEK_END. On error, STATUS is set to a nonzero value. If STATUS the seek fails silently.

This intrinsic routine is not fully backwards compatible with g77. In g77, the

FSEEK takes a statement label instead of a STATUS variable. If FSEEK is used in old code, change

CALL FSEEK(UNIT, OFFSET, WHENCE, *label) to

INTEGER :: status

CALL FSEEK(UNIT, OFFSET, WHENCE, status)

IF (status /= 0) GOTO label

Please note that GNU Fortran provides the Fortran 2003 Stream facility. Programmers should consider the use of new stream IO feature in new code for future portability. See also

Chapter 4 [Fortran 2003 status], page 25 .

Standard : GNU extension

Class: Subroutine

Syntax :

CALL FSEEK(UNIT, OFFSET, WHENCE[, STATUS])

Arguments:

UNIT

OFFSET

WHENCE

STATUS

Shall be a scalar of type INTEGER.

Shall be a scalar of type INTEGER. Its value shall be either 0,

1 or 2.

(Optional) shall be a scalar of type INTEGER(4).

Example:

PROGRAM test_fseek

INTEGER, PARAMETER :: SEEK_SET = 0, SEEK_CUR = 1, SEEK_END = 2

INTEGER :: fd, offset, ierr ierr = 0 offset = 5 fd = 10

OPEN(UNIT=fd, FILE="fseek.test")

CALL FSEEK(fd, offset, SEEK_SET, ierr) ! move to OFFSET print *, FTELL(fd), ierr

! move to end CALL FSEEK(fd, 0, SEEK_END, ierr) print *, FTELL(fd), ierr

CALL FSEEK(fd, 0, SEEK_SET, ierr) print *, FTELL(fd), ierr

! move to beginning

CLOSE(UNIT=fd)

END PROGRAM

86 The GNU Fortran Compiler

See also:

Section 6.82 [FTELL], page 86

6.81 FSTAT — Get file status

Description:

FSTAT is identical to

, except that information about an already opened file is obtained.

The elements in BUFF are the same as described by

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL FSTAT(UNIT, BUFF [, STATUS])

Arguments:

UNIT

BUFF

STATUS

An open I/O unit number of type INTEGER.

The type shall be INTEGER(4), DIMENSION(13).

(Optional) status flag of type INTEGER(4). Returns 0 on success and a system specific error code otherwise.

Example: See

Section 6.80 [FSEEK], page 85

for an example.

6.82 FTELL — Current stream position

Description:

Retrieves the current position within an open file.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL FTELL(UNIT, OFFSET)

OFFSET = FTELL(UNIT)

Arguments:

OFFSET

UNIT

Shall of type INTEGER.

Return value:

In either syntax, OFFSET is set to the current offset of unit number UNIT, or to −1 if the unit is not currently open.

Example:

Chapter 6: Intrinsic Procedures 87

PROGRAM test_ftell

INTEGER :: i

OPEN(10, FILE="temp.dat")

CALL ftell(10,i)

WRITE(*,*) i

END PROGRAM

See also:

6.83 GAMMA — Gamma function

Description:

GAMMA(X) computes Gamma (Γ) of X. For positive, integer values of X the

Gamma function simplifies to the factorial function Γ(x) = (x − 1)!.

Γ(x) =

∞ t x−1 e

−t dt

Standard : GNU Extension

Class: Elemental function

Syntax :

X = GAMMA(X)

Arguments:

X Shall be of type REAL and neither zero nor a negative integer.

Return value:

The return value is of type REAL of the same kind as X.

Example: program test_gamma real :: x = 1.0

x = gamma(x) ! returns 1.0

end program test_gamma

Specific names:

Name

GAMMA(X)

DGAMMA(X)

Argument

REAL(4) X

REAL(8) X

Return type

REAL(4)

REAL(8)

Standard

GNU Extension

See also: Logarithm of the Gamma function:

Section 6.126 [LGAMMA], page 108

6.84 GERROR — Get last system error message

Description:

Returns the system error message corresponding to the last system error. This resembles the functionality of strerror(3) in C.

Standard : GNU extension

Class:

Syntax :

Subroutine

CALL GERROR(RESULT)

Arguments:

RESULT Shall of type CHARACTER(*).

88 The GNU Fortran Compiler

Example:

PROGRAM test_gerror

CHARACTER(len=100) :: msg

CALL gerror(msg)

WRITE(*,*) msg

END PROGRAM

See also:

Section 6.107 [IERRNO], page 99

Section 6.165 [PERROR], page 130

6.85 GETARG — Get command line arguments

Description:

Retrieve the N th argument that was passed on the command line when the containing program was invoked.

This intrinsic routine is provided for backwards compatibility with GNU Fortran

77. In new code, programmers should consider the use of the

Section 6.87

[GET COMMAND ARGUMENT], page 89

intrinsic defined by the Fortran

2003 standard.

Standard : GNU extension

Class: Subroutine

Syntax :

CALL GETARG(POS, VALUE)

Arguments:

POS Shall be of type INTEGER and not wider than the default integer kind; POS ≥ 0

Shall be of type CHARACTER(*).

VALUE

Return value:

After GETARG returns, the VALUE argument holds the POSth command line argument. If VALUE can not hold the argument, it is truncated to fit the length of VALUE. If there are less than POS arguments specified at the command line,

VALUE will be filled with blanks. If POS = 0, VALUE is set to the name of the program (on systems that support this feature).

Example:

PROGRAM test_getarg

INTEGER :: i

CHARACTER(len=32) :: arg

DO i = 1, iargc()

CALL getarg(i, arg)

WRITE (*,*) arg

END DO

END PROGRAM

See also: GNU Fortran 77 compatibility function:

Section 6.100 [IARGC], page 96

F2003 functions and subroutines:

Section 6.86 [GET COMMAND], page 89

Section 6.87 [GET COMMAND ARGUMENT], page 89 ,

Section 6.42 [COM-

Chapter 6: Intrinsic Procedures 89

6.86 GET_COMMAND — Get the entire command line

Description:

Retrieve the entire command line that was used to invoke the program.

Standard : F2003

Class:

Syntax :

Subroutine

CALL GET_COMMAND(CMD)

Arguments:

CMD Shall be of type CHARACTER(*).

Return value:

Stores the entire command line that was used to invoke the program in ARG.

If ARG is not large enough, the command will be truncated.

Example:

PROGRAM test_get_command

CHARACTER(len=255) :: cmd

CALL get_command(cmd)

WRITE (*,*) TRIM(cmd)

END PROGRAM

Section 6.42 [COM-

6.87 GET_COMMAND_ARGUMENT — Get command line arguments

Description:

Retrieve the N th argument that was passed on the command line when the containing program was invoked.

Standard : F2003

Class:

Syntax :

Subroutine

CALL GET_COMMAND_ARGUMENT(N, ARG)

Arguments:

ARG

Shall be of type INTEGER(4), N ≥ 0

Shall be of type CHARACTER(*).

Return value:

After GET_COMMAND_ARGUMENT returns, the ARG argument holds the N th command line argument. If ARG can not hold the argument, it is truncated to fit the length of ARG. If there are less than N arguments specified at the command line, ARG will be filled with blanks. If N = 0, ARG is set to the name of the program (on systems that support this feature).

Example:

PROGRAM test_get_command_argument

INTEGER :: i

CHARACTER(len=32) :: arg

90 The GNU Fortran Compiler i = 0

CALL get_command_argument(i, arg)

IF (LEN_TRIM(arg) == 0) EXIT

WRITE (*,*) TRIM(arg) i = i+1

END DO

END PROGRAM

See also:

Section 6.86

[GET COMMAND], page 89 ,

Section 6.42

[COM-

Section 6.39 [CHDIR], page 59

6.88 GETCWD — Get current working directory

Description:

Get current working directory.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Standard : GNU extension

Class:

Syntax :

Subroutine, function

CALL GETCWD(CWD [, STATUS])

Arguments:

CWD

STATUS

The type shall be CHARACTER(*).

(Optional) status flag. Returns 0 on success, a system specific and nonzero error code otherwise.

Example:

PROGRAM test_getcwd

CHARACTER(len=255) :: cwd

CALL getcwd(cwd)

WRITE(*,*) TRIM(cwd)

END PROGRAM

See also:

6.89 GETENV — Get an environmental variable

Description:

Get the VALUE of the environmental variable ENVVAR.

This intrinsic routine is provided for backwards compatibility with GNU Fortran

77. In new code, programmers should consider the use of the

Section 6.90

[GET ENVIRONMENT VARIABLE], page 91

intrinsic defined by the Fortran

2003 standard.

Standard : GNU extension

Class: Subroutine

Syntax :

CALL GETENV(ENVVAR, VALUE)

Chapter 6: Intrinsic Procedures 91

Arguments:

ENVVAR

VALUE

Return value:

Stores the value of ENVVAR in VALUE. If VALUE is not large enough to hold the data, it is truncated. If ENVVAR is not set, VALUE will be filled with blanks.

Example:

Shall be of type CHARACTER(*).

PROGRAM test_getenv

CHARACTER(len=255) :: homedir

CALL getenv("HOME", homedir)

WRITE (*,*) TRIM(homedir)

END PROGRAM

6.90 GET_ENVIRONMENT_VARIABLE — Get an environmental variable

Description:

Get the VALUE of the environmental variable ENVVAR.

Standard : F2003

Class: Subroutine

Syntax :

CALL GET_ENVIRONMENT_VARIABLE(ENVVAR, VALUE)

Arguments:

ENVVAR

VALUE

Return value:

Stores the value of ENVVAR in VALUE. If VALUE is not large enough to hold the data, it is truncated. If ENVVAR is not set, VALUE will be filled with blanks.

Example:

Shall be of type CHARACTER(*).

PROGRAM test_getenv

CHARACTER(len=255) :: homedir

CALL get_environment_variable("HOME", homedir)

WRITE (*,*) TRIM(homedir)

END PROGRAM

6.91 GETGID — Group ID function

Description:

Returns the numerical group ID of the current process.

Standard : GNU extension

Class: Function

Syntax :

RESULT = GETGID()

92 The GNU Fortran Compiler

Return value:

The return value of GETGID is an INTEGER of the default kind.

Example: See GETPID for an example.

See also:

Section 6.93 [GETPID], page 92

Section 6.94 [GETUID], page 93

6.92 GETLOG — Get login name

Description:

Gets the username under which the program is running.

Standard : GNU extension

Class: Subroutine

Syntax :

CALL GETLOG(LOGIN)

Arguments:

Return value:

Stores the current user name in LOGIN. (On systems where POSIX functions geteuid and getpwuid are not available, and the getlogin function is not implemented either, this will return a blank string.)

Example:

PROGRAM TEST_GETLOG

CHARACTER(32) :: login

CALL GETLOG(login)

WRITE(*,*) login

END PROGRAM

See also:

Section 6.94 [GETUID], page 93

6.93 GETPID — Process ID function

Description:

Returns the numerical process identifier of the current process.

Standard : GNU extension

Class:

Syntax :

Function

RESULT = GETPID()

Return value:

The return value of GETPID is an INTEGER of the default kind.

Example: program info print *, "The current process ID is ", getpid() print *, "Your numerical user ID is ", getuid() print *, "Your numerical group ID is ", getgid() end program info

See also:

Section 6.91 [GETGID], page 91 ,

Section 6.94 [GETUID], page 93

Chapter 6: Intrinsic Procedures 93

6.94 GETUID — User ID function

Description:

Returns the numerical user ID of the current process.

Standard : GNU extension

Class: Function

Syntax :

RESULT = GETUID()

Return value:

The return value of GETUID is an INTEGER of the default kind.

Example: See GETPID for an example.

See also:

Section 6.93 [GETPID], page 92

Section 6.92 [GETLOG], page 92

6.95 GMTIME — Convert time to GMT info

Description:

Given a system time value STIME (as provided by the TIME8() intrinsic), fills TARRAY with values extracted from it appropriate to the UTC time zone

(Universal Coordinated Time, also known in some countries as GMT, Greenwich

Mean Time), using gmtime(3).

Standard : GNU extension

Class:

Syntax :

Subroutine

CALL GMTIME(STIME, TARRAY)

Arguments:

STIME

TARRAY

An INTEGER(*) scalar expression corresponding to a system time, with INTENT(IN).

A default INTEGER array with 9 elements, with INTENT(OUT).

Return value:

The elements of TARRAY are assigned as follows:

1. Seconds after the minute, range 0–59 or 0–61 to allow for leap seconds

2. Minutes after the hour, range 0–59

3. Hours past midnight, range 0–23

4. Day of month, range 0–31

5. Number of months since January, range 0–12

6. Years since 1900

7. Number of days since Sunday, range 0–6

8. Days since January 1

9. Daylight savings indicator: positive if daylight savings is in effect, zero if not, and negative if the information is not available.

See also:

Section 6.140 [LTIME], page 116 ,

Section 6.208

[TIME], page 154

Section 6.104 [ICHAR], page 97

94 The GNU Fortran Compiler

6.96 HOSTNM — Get system host name

Description:

Retrieves the host name of the system on which the program is running.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL HOSTNM(NAME[, STATUS])

STATUS = HOSTNM(NAME)

Arguments:

NAME

STATUS

Shall of type CHARACTER(*).

(Optional) status flag of type INTEGER. Returns 0 on success, or a system specific error code otherwise.

Return value:

In either syntax, NAME is set to the current hostname if it can be obtained, or to a blank string otherwise.

6.97 HUGE — Largest number of a kind

Description:

HUGE(X) returns the largest number that is not an infinity in the model of the type of X.

Standard : F95 and later

Class: Inquiry function

Syntax :

RESULT = HUGE(X)

Arguments:

X Shall be of type REAL or INTEGER.

Return value:

The return value is of the same type and kind as X

Example: program test_huge_tiny print *, huge(0), huge(0.0), huge(0.0d0) print *, tiny(0.0), tiny(0.0d0) end program test_huge_tiny

6.98 IACHAR — Code in

ASCII collating sequence

Description:

IACHAR(C) returns the code for the ASCII character in the first character position of C.

Standard : F95 and later

Chapter 6: Intrinsic Procedures 95

Class: Elemental function

Syntax :

RESULT = IACHAR(C [, KIND])

Arguments:

KIND

Shall be a scalar CHARACTER, with INTENT(IN)

(Optional) An INTEGER initialization expression indicating the kind parameter of the result.

Return value:

The return value is of type INTEGER and of kind KIND. If KIND is absent, the return value is of default integer kind.

Example: program test_iachar integer i i = iachar(’ ’) end program test_iachar

Note: See

for a discussion of converting between numerical values and formatted string representations.

See also:

Section 6.5 [ACHAR], page 39

Section 6.38 [CHAR], page 59 ,

Section 6.104

[ICHAR], page 97

6.99 IAND — Bitwise logical and

Description:

Bitwise logical AND.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = IAND(I, J)

Arguments:

The type shall be INTEGER(*).

The type shall be INTEGER(*), of the same kind as I. (As a

GNU extension, different kinds are also permitted.)

Return value:

The return type is INTEGER(*), of the same kind as the arguments. (If the argument kinds differ, it is of the same kind as the larger argument.)

Example:

PROGRAM test_iand

INTEGER :: a, b

DATA a / Z’F’ /, b / Z’3’ /

WRITE (*,*) IAND(a, b)

END PROGRAM

See also:

Section 6.106 [IEOR], page 99 ,

Section 6.102

Section 6.103 [IBSET], page 97 ,

Section 6.161 [NOT], page 128

96 The GNU Fortran Compiler

6.100 IARGC — Get the number of command line arguments

Description:

IARGC() returns the number of arguments passed on the command line when the containing program was invoked.

This intrinsic routine is provided for backwards compatibility with GNU Fortran

77. In new code, programmers should consider the use of the

Section 6.42

[COMMAND ARGUMENT COUNT], page 62

intrinsic defined by the Fortran

2003 standard.

Standard : GNU extension

Class: Function

Syntax :

RESULT = IARGC()

Arguments:

None.

Return value:

The number of command line arguments, type INTEGER(4).

Example: See

Section 6.85 [GETARG], page 88

See also: GNU Fortran 77 compatibility subroutine:

Section 6.85 [GETARG], page 88

F2003 functions and subroutines:

Section 6.86 [GET COMMAND], page 89

Section 6.87 [GET COMMAND ARGUMENT], page 89 ,

Section 6.42 [COM-

6.101 IBCLR — Clear bit

Description:

IBCLR returns the value of I with the bit at position POS set to zero.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = IBCLR(I, POS)

Arguments:

POS

The type shall be INTEGER(*).

Return value:

The return value is of type INTEGER(*) and of the same kind as I.

Section 6.99

[IAND], page 95 ,

Section 6.157 [MVBITS], page 126

Chapter 6: Intrinsic Procedures 97

6.102 IBITS — Bit extraction

Description:

IBITS extracts a field of length LEN from I, starting from bit position POS and extending left for LEN bits. The result is right-justified and the remaining bits are zeroed. The value of POS+LEN must be less than or equal to the value

BIT_SIZE(I).

Standard : F95 and later

Class:

Syntax :

Elemental function

RESULT = IBITS(I, POS, LEN)

Arguments:

POS

LEN

The type shall be INTEGER(*).

Return value:

The return value is of type INTEGER(*) and of the same kind as I.

See also:

Section 6.30 [BIT SIZE], page 54 ,

Section 6.103

[IBSET], page 97

Section 6.101 [IBCLR], page 96

6.103 IBSET — Set bit

Description:

IBSET returns the value of I with the bit at position POS set to one.

Standard : F95 and later

Class:

Syntax :

Elemental function

RESULT = IBSET(I, POS)

Arguments:

POS

The type shall be INTEGER(*).

Return value:

The return value is of type INTEGER(*) and of the same kind as I.

See also:

Section 6.102 [IBITS], page 97

Section 6.99

[IAND], page 95 ,

Section 6.157 [MVBITS], page 126

6.104 ICHAR — Character-to-integer conversion function

Description:

ICHAR(C) returns the code for the character in the first character position of

C in the system’s native character set. The correspondence between characters and their codes is not necessarily the same across different GNU Fortran implementations.

98 The GNU Fortran Compiler

Standard : F95 and later

Class:

Syntax :

Elemental function

RESULT = ICHAR(C [, KIND])

Arguments:

KIND

Shall be a scalar CHARACTER, with INTENT(IN)

(Optional) An INTEGER initialization expression indicating the kind parameter of the result.

Return value:

The return value is of type INTEGER and of kind KIND. If KIND is absent, the return value is of default integer kind.

Example: program test_ichar integer i i = ichar(’ ’) end program test_ichar

Note: No intrinsic exists to convert between a numeric value and a formatted character string representation – for instance, given the CHARACTER value ’154’, obtaining an INTEGER or REAL value with the value 154, or vice versa. Instead, this functionality is provided by internal-file I/O, as in the following example: program read_val integer value character(len=10) string, string2 string = ’154’

! Convert a string to a numeric value read (string,’(I10)’) value print *, value

! Convert a value to a formatted string write (string2,’(I10)’) value print *, string2 end program read_val

See also:

Section 6.5 [ACHAR], page 39

Section 6.38 [CHAR], page 59

Section 6.98

[IACHAR], page 94

6.105 IDATE — Get current local time subroutine

(day/month/year)

Description:

IDATE(TARRAY) Fills TARRAY with the numerical values at the current local time. The day (in the range 1-31), month (in the range 1-12), and year appear in elements 1, 2, and 3 of TARRAY, respectively. The year has four significant digits.

Standard : GNU extension

Class: Subroutine

Syntax :

CALL IDATE(TARRAY)

Chapter 6: Intrinsic Procedures 99

Arguments:

TARRAY

Return value:

Does not return.

The type shall be INTEGER, DIMENSION(3) and the kind shall be the default integer kind.

Example: program test_idate integer, dimension(3) :: tarray call idate(tarray) print *, tarray(1) print *, tarray(2) print *, tarray(3) end program test_idate

6.106 IEOR — Bitwise logical exclusive or

Description:

IEOR returns the bitwise boolean exclusive-OR of I and J.

Standard : F95 and later

Class:

Syntax :

Elemental function

RESULT = IEOR(I, J)

Arguments:

The type shall be INTEGER(*).

The type shall be INTEGER(*), of the same kind as I. (As a

GNU extension, different kinds are also permitted.)

Return value:

The return type is INTEGER(*), of the same kind as the arguments. (If the argument kinds differ, it is of the same kind as the larger argument.)

See also:

Section 6.102

Section 6.103 [IBSET], page 97 ,

Section 6.161 [NOT], page 128

6.107 IERRNO — Get the last system error number

Description:

Returns the last system error number, as given by the C errno() function.

Standard : GNU extension

Class: Function

Syntax :

RESULT = IERRNO()

Arguments:

None.

Return value:

The return value is of type INTEGER and of the default integer kind.

See also:

Section 6.165 [PERROR], page 130

100 The GNU Fortran Compiler

6.108 INDEX — Position of a substring within a string

Description:

Returns the position of the start of the first occurrence of string SUBSTRING as a substring in STRING, counting from one. If SUBSTRING is not present in STRING, zero is returned. If the BACK argument is present and true, the return value is the start of the last occurrence rather than the first.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = INDEX(STRING, SUBSTRING [, BACK [, KIND]])

Arguments:

STRING Shall be a scalar CHARACTER(*), with INTENT(IN)

SUBSTRING Shall be a scalar CHARACTER(*), with INTENT(IN)

BACK

KIND

(Optional) Shall be a scalar LOGICAL(*), with INTENT(IN)

(Optional) An INTEGER initialization expression indicating the kind parameter of the result.

Return value:

The return value is of type INTEGER and of kind KIND. If KIND is absent, the return value is of default integer kind.

See also:

Section 6.182 [SCAN], page 139 ,

Section 6.219 [VERIFY], page 159

6.109 INT — Convert to integer type

Description:

Convert to integer type

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = INT(A [, KIND))

Arguments:

KIND

Shall be of type INTEGER(*), REAL(*), or COMPLEX(*).

(Optional) An INTEGER(*) initialization expression indicating the kind parameter of the result.

Return value:

These functions return a INTEGER(*) variable or array under the following rules:

(A)

(B)

(C)

If A is of type INTEGER(*), INT(A) = A

If A is of type REAL(*) and |A| < 1, INT(A) equals 0. If |A| ≥ 1, then INT(A) equals the largest integer that does not exceed the range of A and whose sign is the same as the sign of A.

If A is of type COMPLEX(*), rule B is applied to the real part of A.

Example:

Chapter 6: Intrinsic Procedures 101 program test_int integer :: i = 42 complex :: z = (-3.7, 1.0) print *, int(i) print *, int(z), int(z,8) end program

Specific names:

Name

IFIX(A)

IDINT(A)

Argument

REAL(4) A

REAL(8) A

Return type

INTEGER

Standard

F77 and later

6.110 INT2 — Convert to 16-bit integer type

Description:

Convert to a KIND=2 integer type. This is equivalent to the standard INT intrinsic with an optional argument of KIND=2, and is only included for backwards compatibility.

The SHORT intrinsic is equivalent to INT2.

Standard : GNU extension.

Class: Elemental function

Syntax :

RESULT = INT2(A)

Arguments:

A Shall be of type INTEGER(*), REAL(*), or COMPLEX(*).

Return value:

The return value is a INTEGER(2) variable.

See also:

Section 6.109 [INT], page 100

Section 6.111 [INT8], page 101 ,

Section 6.137

[LONG], page 114

6.111 INT8 — Convert to 64-bit integer type

Description:

Convert to a KIND=8 integer type. This is equivalent to the standard INT intrinsic with an optional argument of KIND=8, and is only included for backwards compatibility.

Standard : GNU extension.

Class: Elemental function

Syntax :

RESULT = INT8(A)

Arguments:

A Shall be of type INTEGER(*), REAL(*), or COMPLEX(*).

Return value:

The return value is a INTEGER(8) variable.

See also:

Section 6.109 [INT], page 100

Section 6.110 [INT2], page 101 ,

Section 6.137

[LONG], page 114

102 The GNU Fortran Compiler

6.112 IOR — Bitwise logical or

Description:

IOR returns the bitwise boolean inclusive-OR of I and J.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = IOR(I, J)

Arguments:

The type shall be INTEGER(*).

The type shall be INTEGER(*), of the same kind as I. (As a

GNU extension, different kinds are also permitted.)

Return value:

The return type is INTEGER(*), of the same kind as the arguments. (If the argument kinds differ, it is of the same kind as the larger argument.)

See also:

Section 6.99 [IAND], page 95

Section 6.102

Section 6.103 [IBSET], page 97 ,

Section 6.161 [NOT], page 128

6.113 IRAND — Integer pseudo-random number

Description:

IRAND(FLAG) returns a pseudo-random number from a uniform distribution between 0 and a system-dependent limit (which is in most cases 2147483647).

If FLAG is 0, the next number in the current sequence is returned; if FLAG is

1, the generator is restarted by CALL SRAND(0); if FLAG has any other value, it is used as a new seed with SRAND.

This intrinsic routine is provided for backwards compatibility with GNU Fortran

77. It implements a simple modulo generator as provided by g77. For new code, one should consider the use of

Section 6.214 [TTYNAM], page 157

as it implements a superior algorithm.

Standard : GNU extension

Class: Function

Syntax :

RESULT = IRAND(FLAG)

Arguments:

FLAG Shall be a scalar INTEGER of kind 4.

Return value:

The return value is of INTEGER(kind=4) type.

Example: program test_irand integer,parameter :: seed = 86456 call srand(seed) print *, irand(), irand(), irand(), irand() print *, irand(seed), irand(), irand(), irand() end program test_irand

Chapter 6: Intrinsic Procedures 103

6.114 IS_IOSTAT_END — Test for end-of-file value

Description:

IS_IOSTAT_END tests whether an variable has the value of the I/O status “end of file”. The function is equivalent to comparing the variable with the IOSTAT_END parameter of the intrinsic module ISO_FORTRAN_ENV.

Standard : Fortran 2003.

Class:

Syntax :

Elemental function

RESULT = IS_IOSTAT_END(I)

Arguments:

I Shall be of the type INTEGER.

Return value:

Returns a LOGICAL of the default kind, which .TRUE. if I has the value which indicates an end of file condition for IOSTAT= specifiers, and is .FALSE. otherwise.

Example:

PROGRAM iostat

IMPLICIT NONE

INTEGER :: stat, i

OPEN(88, FILE=’test.dat’)

READ(88, *, IOSTAT=stat) i

IF(IS_IOSTAT_END(stat)) STOP ’END OF FILE’

END PROGRAM

6.115 IS_IOSTAT_EOR — Test for end-of-record value

Description:

IS_IOSTAT_EOR tests whether an variable has the value of the I/O status “end of record”. The function is equivalent to comparing the variable with the IOSTAT_

EOR parameter of the intrinsic module ISO_FORTRAN_ENV.

Standard : Fortran 2003.

Class:

Syntax :

Elemental function

RESULT = IS_IOSTAT_EOR(I)

Arguments:

I Shall be of the type INTEGER.

Return value:

Returns a LOGICAL of the default kind, which .TRUE. if I has the value which indicates an end of file condition for IOSTAT= specifiers, and is .FALSE. otherwise.

Example:

PROGRAM iostat

IMPLICIT NONE

INTEGER :: stat, i(50)

OPEN(88, FILE=’test.dat’, FORM=’UNFORMATTED’)

104 The GNU Fortran Compiler

READ(88, IOSTAT=stat) i

IF(IS_IOSTAT_EOR(stat)) STOP ’END OF RECORD’

END PROGRAM

6.116 ISATTY — Whether a unit is a terminal device.

Description:

Determine whether a unit is connected to a terminal device.

Standard : GNU extension.

Class:

Syntax :

Function

RESULT = ISATTY(UNIT)

Arguments:

UNIT Shall be a scalar INTEGER(*).

Return value:

Returns .TRUE. if the UNIT is connected to a terminal device, .FALSE. otherwise.

Example:

PROGRAM test_isatty

INTEGER(kind=1) :: unit

DO unit = 1, 10 write(*,*) isatty(unit=unit)

END DO

END PROGRAM

See also:

6.117 ISHFT — Shift bits

Description:

ISHFT returns a value corresponding to I with all of the bits shifted SHIFT places. A value of SHIFT greater than zero corresponds to a left shift, a value of zero corresponds to no shift, and a value less than zero corresponds to a right shift. If the absolute value of SHIFT is greater than BIT_SIZE(I), the value is undefined. Bits shifted out from the left end or right end are lost; zeros are shifted in from the opposite end.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = ISHFT(I, SHIFT)

Arguments:

SHIFT

The type shall be INTEGER(*).

Return value:

The return value is of type INTEGER(*) and of the same kind as I.

See also:

Section 6.118 [ISHFTC], page 105

Chapter 6: Intrinsic Procedures 105

6.118 ISHFTC — Shift bits circularly

Description:

ISHFTC returns a value corresponding to I with the rightmost SIZE bits shifted circularly SHIFT places; that is, bits shifted out one end are shifted into the opposite end. A value of SHIFT greater than zero corresponds to a left shift, a value of zero corresponds to no shift, and a value less than zero corresponds to a right shift. The absolute value of SHIFT must be less than SIZE. If the

SIZE argument is omitted, it is taken to be equivalent to BIT_SIZE(I).

Standard : F95 and later

Class:

Syntax :

Elemental function

RESULT = ISHFTC(I, SHIFT [, SIZE])

Arguments:

SHIFT

SIZE

The type shall be INTEGER(*).

(Optional) The type shall be INTEGER(*); the value must be greater than zero and less than or equal to BIT_SIZE(I).

Return value:

The return value is of type INTEGER(*) and of the same kind as I.

See also:

Section 6.117 [ISHFT], page 104

6.119 ISNAN — Test for a NaN

Description:

ISNAN tests whether a floating-point value is an IEEE Not-a-Number (NaN).

Standard : GNU extension

Class: Elemental function

Syntax :

ISNAN(X)

Arguments:

X Variable of the type REAL.

Return value:

Returns a default-kind LOGICAL. The returned value is TRUE if X is a NaN and

FALSE otherwise.

Example: program test_nan implicit none real :: x x = -1.0

x = sqrt(x) if (isnan(x)) stop ’"x" is a NaN’ end program test_nan

106 The GNU Fortran Compiler

6.120 ITIME — Get current local time subroutine

(hour/minutes/seconds)

Description:

IDATE(TARRAY) Fills TARRAY with the numerical values at the current local time. The hour (in the range 1-24), minute (in the range 1-60), and seconds (in the range 1-60) appear in elements 1, 2, and 3 of TARRAY, respectively.

Standard : GNU extension

Class: Subroutine

Syntax :

CALL ITIME(TARRAY)

Arguments:

TARRAY

Return value:

Does not return.

The type shall be INTEGER, DIMENSION(3) and the kind shall be the default integer kind.

Example: program test_itime integer, dimension(3) :: tarray call itime(tarray) print *, tarray(1) print *, tarray(2) print *, tarray(3) end program test_itime

6.121 KILL — Send a signal to a process

Description:

Standard : Sends the signal specified by SIGNAL to the process PID. See kill(2).

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Class:

Syntax :

Subroutine, function

CALL KILL(PID, SIGNAL [, STATUS])

Arguments:

PID

SIGNAL

STATUS

Shall be a scalar INTEGER, with INTENT(IN)

(Optional) status flag of type INTEGER(4) or INTEGER(8).

Returns 0 on success, or a system-specific error code otherwise.

See also:

Section 6.2 [ABORT], page 37 ,

Section 6.66 [EXIT], page 77

6.122 KIND — Kind of an entity

Description:

KIND(X) returns the kind value of the entity X.

Standard : F95 and later

Chapter 6: Intrinsic Procedures 107

Class: Inquiry function

Syntax :

K = KIND(X)

Arguments:

X Shall be of type LOGICAL, INTEGER, REAL, COMPLEX or

CHARACTER.

Return value:

The return value is a scalar of type INTEGER and of the default integer kind.

Example: program test_kind integer,parameter :: kc = kind(’ ’) integer,parameter :: kl = kind(.true.) print *, "The default character kind is ", kc print *, "The default logical kind is ", kl end program test_kind

6.123 LBOUND — Lower dimension bounds of an array

Description:

Returns the lower bounds of an array, or a single lower bound along the DIM dimension.

Standard : F95 and later

Class: Inquiry function

Syntax :

RESULT = LBOUND(ARRAY [, DIM [, KIND]])

Arguments:

ARRAY

DIM

KIND

Shall be an array, of any type.

(Optional) Shall be a scalar INTEGER(*).

(Optional) An INTEGER initialization expression indicating the kind parameter of the result.

Return value:

The return value is of type INTEGER and of kind KIND. If KIND is absent, the return value is of default integer kind. If DIM is absent, the result is an array of the lower bounds of ARRAY. If DIM is present, the result is a scalar corresponding to the lower bound of the array along that dimension. If ARRAY is an expression rather than a whole array or array structure component, or if it has a zero extent along the relevant dimension, the lower bound is taken to be 1.

See also:

Section 6.215 [UBOUND], page 158

6.124 LEN — Length of a character entity

Description:

Returns the length of a character string. If STRING is an array, the length of an element of STRING is returned. Note that STRING need not be defined when

108 The GNU Fortran Compiler this intrinsic is invoked, since only the length, not the content, of STRING is needed.

Standard : F77 and later

Class:

Syntax :

Inquiry function

L = LEN(STRING [, KIND])

Arguments:

STRING

KIND

Shall be a scalar or array of type CHARACTER(*), with

INTENT(IN)

(Optional) An INTEGER initialization expression indicating the kind parameter of the result.

Return value:

The return value is of type INTEGER and of kind KIND. If KIND is absent, the return value is of default integer kind.

See also:

Section 6.125 [LEN TRIM], page 108 ,

Section 6.9 [ADJUSTR], page 41

6.125 LEN_TRIM — Length of a character entity without trailing blank characters

Description:

Returns the length of a character string, ignoring any trailing blanks.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = LEN_TRIM(STRING [, KIND])

Arguments:

STRING

KIND

Shall be a scalar of type CHARACTER(*), with INTENT(IN)

(Optional) An INTEGER initialization expression indicating the kind parameter of the result.

Return value:

The return value is of type INTEGER and of kind KIND. If KIND is absent, the return value is of default integer kind.

See also:

Section 6.124 [LEN], page 107

Section 6.128 [LGT], page 110 ,

Section 6.9

[ADJUSTR], page 41

6.126 LGAMMA — Logarithm of the Gamma function

Description:

GAMMA(X) computes the natural logrithm of the absolute value of the Gamma

(Γ) function.

Standard : GNU Extension

Class: Elemental function

Chapter 6: Intrinsic Procedures 109

Syntax :

X = LGAMMA(X)

Arguments:

X Shall be of type REAL and neither zero nor a negative integer.

Return value:

The return value is of type REAL of the same kind as X.

Example: program test_log_gamma real :: x = 1.0

x = lgamma(x) ! returns 0.0

end program test_log_gamma

Specific names:

Name

LGAMMA(X)

ALGAMA(X)

DLGAMA(X)

Argument

REAL(4) X

REAL(8) X

Return type

REAL(4)

REAL(8)

6.127 LGE — Lexical greater than or equal

Description:

Determines whether one string is lexically greater than or equal to another string, where the two strings are interpreted as containing ASCII character codes. If the String A and String B are not the same length, the shorter is compared as if spaces were appended to it to form a value that has the same length as the longer.

In general, the lexical comparison intrinsics LGE, LGT, LLE, and LLT differ from the corresponding intrinsic operators .GE., .GT., .LE., and .LT., in that the latter use the processor’s character ordering (which is not ASCII on some targets), whereas the former always use the ASCII ordering.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = LGE(STRING_A, STRING_B)

Arguments:

STRING A

STRING B

Shall be of default CHARACTER type.

Return value:

Returns .TRUE. if STRING_A >= STRING_B, and .FALSE. otherwise, based on the ASCII ordering.

See also:

Section 6.130 [LLE], page 111

Section 6.131

[LLT], page 111

110 The GNU Fortran Compiler

6.128 LGT — Lexical greater than

Description:

Determines whether one string is lexically greater than another string, where the two strings are interpreted as containing ASCII character codes. If the

String A and String B are not the same length, the shorter is compared as if spaces were appended to it to form a value that has the same length as the longer.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = LGT(STRING_A, STRING_B)

Arguments:

STRING A

STRING B

Shall be of default CHARACTER type.

Return value:

Returns .TRUE. if STRING_A > STRING_B, and .FALSE. otherwise, based on the

ASCII ordering.

See also:

Section 6.127 [LGE], page 109

Section 6.130 [LLE], page 111

Section 6.131

[LLT], page 111

6.129 LINK — Create a hard link

Description:

Makes a (hard) link from file PATH1 to PATH2. A null character (CHAR(0)) can be used to mark the end of the names in PATH1 and PATH2; otherwise, trailing blanks in the file names are ignored. If the STATUS argument is supplied, it contains 0 on success or a nonzero error code upon return; see link(2).

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL LINK(PATH1, PATH2 [, STATUS])

STATUS = LINK(PATH1, PATH2)

Arguments:

PATH1

PATH2

STATUS

Shall be of default CHARACTER type.

(Optional) Shall be of default INTEGER type.

See also:

Section 6.203 [SYMLNK], page 151 ,

Section 6.217 [UNLINK], page 158

Chapter 6: Intrinsic Procedures 111

6.130 LLE — Lexical less than or equal

Description:

Determines whether one string is lexically less than or equal to another string, where the two strings are interpreted as containing ASCII character codes. If the String A and String B are not the same length, the shorter is compared as if spaces were appended to it to form a value that has the same length as the longer.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = LLE(STRING_A, STRING_B)

Arguments:

STRING A

STRING B

Shall be of default CHARACTER type.

Return value:

Returns .TRUE. if STRING_A <= STRING_B, and .FALSE. otherwise, based on the ASCII ordering.

See also:

Section 6.127 [LGE], page 109

Section 6.128 [LGT], page 110 ,

Section 6.131

[LLT], page 111

6.131 LLT — Lexical less than

Description:

Determines whether one string is lexically less than another string, where the two strings are interpreted as containing ASCII character codes. If the String

A and String B are not the same length, the shorter is compared as if spaces were appended to it to form a value that has the same length as the longer.

Standard : F77 and later

Class:

Syntax :

Elemental function

RESULT = LLT(STRING_A, STRING_B)

Arguments:

STRING A

STRING B

Shall be of default CHARACTER type.

112 The GNU Fortran Compiler

Return value:

Returns .TRUE. if STRING_A < STRING_B, and .FALSE. otherwise, based on the

ASCII ordering.

See also:

Section 6.127 [LGE], page 109

Section 6.128 [LGT], page 110 ,

Section 6.130

[LLE], page 111

6.132 LNBLNK — Index of the last non-blank character in a string

Description:

Returns the length of a character string, ignoring any trailing blanks. This is identical to the standard LEN_TRIM intrinsic, and is only included for backwards compatibility.

Standard : GNU extension

Class: Elemental function

Syntax :

RESULT = LNBLNK(STRING)

Arguments:

STRING Shall be a scalar of type CHARACTER(*), with INTENT(IN)

Return value:

The return value is of INTEGER(kind=4) type.

Section 6.125 [LEN TRIM], page 108

6.133 LOC — Returns the address of a variable

Description:

LOC(X) returns the address of X as an integer.

Standard : GNU extension

Class: Inquiry function

Syntax :

RESULT = LOC(X)

Arguments:

X Variable of any type.

Return value:

The return value is of type INTEGER, with a KIND corresponding to the size (in bytes) of a memory address on the target machine.

Example: program test_loc integer :: i real :: r i = loc(r) print *, i end program test_loc

Chapter 6: Intrinsic Procedures 113

6.134 LOG — Logarithm function

Description:

LOG(X) computes the logarithm of X.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = LOG(X)

Arguments:

X The type shall be REAL(*) or COMPLEX(*).

Return value:

The return value is of type REAL(*) or COMPLEX(*). The kind type parameter is the same as X.

Example: program test_log real(8) :: x = 1.0_8

complex :: z = (1.0, 2.0) x = log(x) z = log(z) end program test_log

Specific names:

Name

ALOG(X)

DLOG(X)

CLOG(X)

ZLOG(X)

CDLOG(X)

Argument

REAL(4) X

Return type

REAL(4)

REAL(8) X REAL(8)

COMPLEX(4) X COMPLEX(4)

COMPLEX(8) X COMPLEX(8)

Standard f95, gnu f95, gnu f95, gnu f95, gnu f95, gnu

6.135 LOG10 — Base 10 logarithm function

Description:

LOG10(X) computes the base 10 logarithm of X.

Standard : F77 and later

Class:

Syntax :

Elemental function

RESULT = LOG10(X)

Arguments:

X The type shall be REAL(*).

Return value:

The return value is of type REAL(*) or COMPLEX(*). The kind type parameter is the same as X.

Example: program test_log10 real(8) :: x = 10.0_8

x = log10(x) end program test_log10

114 The GNU Fortran Compiler

Specific names:

Name

ALOG10(X)

DLOG10(X)

Argument

REAL(4) X

REAL(8) X

Return type

REAL(4)

REAL(8)

Standard

F95 and later

6.136 LOGICAL — Convert to logical type

Description:

Converts one kind of LOGICAL variable to another.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = LOGICAL(L [, KIND])

Arguments:

KIND

The type shall be LOGICAL(*).

(Optional) An INTEGER(*) initialization expression indicating the kind parameter of the result.

Return value:

The return value is a LOGICAL value equal to L, with a kind corresponding to

KIND, or of the default logical kind if KIND is not given.

See also:

Section 6.109 [INT], page 100 ,

Section 6.175 [REAL], page 135 ,

Section 6.41

[CMPLX], page 61

6.137 LONG — Convert to integer type

Description:

Convert to a KIND=4 integer type, which is the same size as a C long integer.

This is equivalent to the standard INT intrinsic with an optional argument of

KIND=4, and is only included for backwards compatibility.

Standard : GNU extension.

Class: Elemental function

Syntax :

RESULT = LONG(A)

Arguments:

A Shall be of type INTEGER(*), REAL(*), or COMPLEX(*).

Return value:

The return value is a INTEGER(4) variable.

See also:

Section 6.109 [INT], page 100

Section 6.110 [INT2], page 101 , Section 6.111

[INT8], page 101

Chapter 6: Intrinsic Procedures 115

6.138 LSHIFT — Left shift bits

Description:

LSHIFT returns a value corresponding to I with all of the bits shifted left by

SHIFT places. If the absolute value of SHIFT is greater than BIT_SIZE(I), the value is undefined. Bits shifted out from the left end are lost; zeros are shifted in from the opposite end.

This function has been superseded by the ISHFT intrinsic, which is standard in

Fortran 95 and later.

Standard : GNU extension

Class:

Syntax :

Elemental function

RESULT = LSHIFT(I, SHIFT)

Arguments:

SHIFT

The type shall be INTEGER(*).

Return value:

The return value is of type INTEGER(*) and of the same kind as I.

See also:

Section 6.117 [ISHFT], page 104 ,

Section 6.118 [ISHFTC], page 105

Section 6.180 [RSHIFT], page 138

6.139 LSTAT — Get file status

Description:

LSTAT is identical to

, except that if path is a symbolic link, then the link itself is statted, not the file that it refers to.

The elements in BUFF are the same as described by

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Standard : GNU extension

Class:

Syntax :

Subroutine, function

CALL LSTAT(FILE, BUFF [, STATUS])

Arguments:

FILE

BUFF

STATUS

The type shall be CHARACTER(*), a valid path within the file system.

The type shall be INTEGER(4), DIMENSION(13).

(Optional) status flag of type INTEGER(4). Returns 0 on success and a system specific error code otherwise.

Example: See

for an example.

6.140 LTIME — Convert time to local time info

Description:

Given a system time value STIME (as provided by the TIME8() intrinsic), fills

TARRAY with values extracted from it appropriate to the local time zone using localtime(3).

Standard : GNU extension

Class:

Syntax :

Subroutine

CALL LTIME(STIME, TARRAY)

Arguments:

STIME

TARRAY

An INTEGER(*) scalar expression corresponding to a system time, with INTENT(IN).

A default INTEGER array with 9 elements, with INTENT(OUT).

Return value:

The elements of TARRAY are assigned as follows:

1. Seconds after the minute, range 0–59 or 0–61 to allow for leap seconds

2. Minutes after the hour, range 0–59

3. Hours past midnight, range 0–23

4. Day of month, range 0–31

5. Number of months since January, range 0–12

6. Years since 1900

7. Number of days since Sunday, range 0–6

8. Days since January 1

9. Daylight savings indicator: positive if daylight savings is in effect, zero if not, and negative if the information is not available.

See also:

Section 6.208

[TIME], page 154

Section 6.79 [FREE], page 84

6.141 MALLOC — Allocate dynamic memory

Description:

MALLOC(SIZE) allocates SIZE bytes of dynamic memory and returns the address of the allocated memory. The MALLOC intrinsic is an extension intended to be used with Cray pointers, and is provided in GNU Fortran to allow the user to compile legacy code. For new code using Fortran 95 pointers, the memory allocation intrinsic is ALLOCATE.

Standard : GNU extension

Class: Function

Syntax :

PTR = MALLOC(SIZE)

Arguments:

SIZE The type shall be INTEGER(*).

Chapter 6: Intrinsic Procedures 117

Return value:

The return value is of type INTEGER(K), with K such that variables of type

INTEGER(K) have the same size as C pointers (sizeof(void *)).

Example: The following example demonstrates the use of MALLOC and FREE with Cray pointers. This example is intended to run on 32-bit systems, where the default integer kind is suitable to store pointers; on 64-bit systems, ptr x would need to be declared as integer(kind=8).

program test_malloc integer i integer ptr_x real*8 x(*), z pointer(ptr_x,x) ptr_x = malloc(20*8) do i = 1, 20 x(i) = sqrt(1.0d0 / i) end do z = 0 do i = 1, 20 z = z + x(i) print *, z end do call free(ptr_x) end program test_malloc

See also:

6.142 MATMUL — matrix multiplication

Description:

Performs a matrix multiplication on numeric or logical arguments.

Standard : F95 and later

Class: Transformational function

Syntax :

RESULT = MATMUL(MATRIX_A, MATRIX_B)

Arguments:

MATRIX A An array of

INTEGER(*), REAL(*), COMPLEX(*), or

LOGICAL(*) type, with a rank of one or two.

MATRIX B An array of INTEGER(*), REAL(*), or COMPLEX(*) type if

MATRIX A is of a numeric type; otherwise, an array of

LOGICAL(*) type.

The rank shall be one or two, and the first (or only) dimension of MATRIX B shall be equal to the last (or only) dimension of MATRIX A.

Return value:

The matrix product of MATRIX A and MATRIX B. The type and kind of the result follow the usual type and kind promotion rules, as for the * or .AND.

operators.

See also:

118 The GNU Fortran Compiler

6.143 MAX — Maximum value of an argument list

Description:

Returns the argument with the largest (most positive) value.

Standard : F77 and later

Class:

Syntax :

Elemental function

RESULT = MAX(A1, A2 [, A3 [, ...]])

Arguments:

A2, A3, ...

The type shall be INTEGER(*) or REAL(*).

An expression of the same type and kind as A1. (As a GNU extension, arguments of different kinds are permitted.)

Return value:

The return value corresponds to the maximum value among the arguments, and has the same type and kind as the first argument.

Specific names:

Name

MAX0(I)

AMAX0(I)

MAX1(X)

AMAX1(X)

DMAX1(X)

Argument Return type Standard

INTEGER(4) I INTEGER(4)

F77 and later

INTEGER(4) I REAL(MAX(X))

F77 and later

REAL(*) X

REAL(4) X

REAL(8) X

INT(MAX(X))

REAL(4)

REAL(8)

F77 and later

Section 6.150 [MIN], page 121

6.144 MAXEXPONENT — Maximum exponent of a real kind

Description:

MAXEXPONENT(X) returns the maximum exponent in the model of the type of X.

Standard : F95 and later

Class: Inquiry function

Syntax :

RESULT = MAXEXPONENT(X)

Arguments:

X Shall be of type REAL.

Return value:

The return value is of type INTEGER and of the default integer kind.

Example: program exponents real(kind=4) :: x real(kind=8) :: y print *, minexponent(x), maxexponent(x) print *, minexponent(y), maxexponent(y) end program exponents

Chapter 6: Intrinsic Procedures 119

6.145 MAXLOC — Location of the maximum value within an array

Description:

Determines the location of the element in the array with the maximum value, or, if the DIM argument is supplied, determines the locations of the maximum element along each row of the array in the DIM direction. If MASK is present, only the elements for which MASK is .TRUE. are considered. If more than one element in the array has the maximum value, the location returned is that of the first such element in array element order. If the array has zero size, or all of the elements of MASK are .FALSE., then the result is an array of zeroes.

Similarly, if DIM is supplied and all of the elements of MASK along a given row are zero, the result value for that row is zero.

Standard : F95 and later

Class: Transformational function

Syntax :

RESULT = MAXLOC(ARRAY, DIM [, MASK])

RESULT = MAXLOC(ARRAY [, MASK])

Arguments:

ARRAY

DIM

MASK

Shall be an array of type INTEGER(*),

REAL(*), or

CHARACTER(*).

(Optional) Shall be a scalar of type INTEGER(*), with a value between one and the rank of ARRAY, inclusive. It may not be an optional dummy argument.

Shall be an array of type LOGICAL(*), and conformable with

ARRAY.

Return value:

If DIM is absent, the result is a rank-one array with a length equal to the rank of ARRAY. If DIM is present, the result is an array with a rank one less than the rank of ARRAY, and a size corresponding to the size of ARRAY with the

DIM dimension removed. If DIM is present and ARRAY has a rank of one, the result is a scalar. In all cases, the result is of default INTEGER type.

See also:

Section 6.143 [MAX], page 118 ,

Section 6.146 [MAXVAL], page 119

6.146 MAXVAL — Maximum value of an array

Description:

Determines the maximum value of the elements in an array value, or, if the

DIM argument is supplied, determines the maximum value along each row of the array in the DIM direction. If MASK is present, only the elements for which MASK is .TRUE. are considered. If the array has zero size, or all of the elements of MASK are .FALSE., then the result is the most negative number of the type and kind of ARRAY if ARRAY is numeric, or a string of nulls if

ARRAY is of character type.

Standard : F95 and later

120 The GNU Fortran Compiler

Class: Transformational function

Syntax :

RESULT = MAXVAL(ARRAY, DIM [, MASK])

RESULT = MAXVAL(ARRAY [, MASK])

Arguments:

ARRAY

DIM

MASK

Shall be an array of type INTEGER(*),

REAL(*), or

CHARACTER(*).

(Optional) Shall be a scalar of type INTEGER(*), with a value between one and the rank of ARRAY, inclusive. It may not be an optional dummy argument.

Shall be an array of type LOGICAL(*), and conformable with

ARRAY.

Return value:

If DIM is absent, or if ARRAY has a rank of one, the result is a scalar. If DIM is present, the result is an array with a rank one less than the rank of ARRAY, and a size corresponding to the size of ARRAY with the DIM dimension removed.

In all cases, the result is of the same type and kind as ARRAY.

See also:

Section 6.143 [MAX], page 118 ,

Section 6.145 [MAXLOC], page 119

6.147 MCLOCK — Time function

Description:

Returns the number of clock ticks since the start of the process, based on the

UNIX function clock(3).

This intrinsic is not fully portable, such as to systems with 32-bit INTEGER types but supporting times wider than 32 bits. Therefore, the values returned by this intrinsic might be, or become, negative, or numerically less than previous values, during a single run of the compiled program.

Standard : GNU extension

Class: Function

Syntax :

RESULT = MCLOCK()

Return value:

The return value is a scalar of type INTEGER(4), equal to the number of clock ticks since the start of the process, or -1 if the system does not support clock(3).

See also:

Section 6.147 [MCLOCK], page 120

Section 6.208 [TIME], page 154

6.148 MCLOCK8 — Time function (64-bit)

Description:

Returns the number of clock ticks since the start of the process, based on the

UNIX function clock(3).

Chapter 6: Intrinsic Procedures 121

Warning: this intrinsic does not increase the range of the timing values over that returned by clock(3). On a system with a 32-bit clock(3), MCLOCK8() will return a 32-bit value, even though it is converted to a 64-bit INTEGER(8) value. That means overflows of the 32-bit value can still occur. Therefore, the values returned by this intrinsic might be or become negative or numerically less than previous values during a single run of the compiled program.

Standard : GNU extension

Class:

Syntax :

Function

RESULT = MCLOCK8()

Return value:

The return value is a scalar of type INTEGER(8), equal to the number of clock ticks since the start of the process, or -1 if the system does not support clock(3).

See also:

Section 6.147 [MCLOCK], page 120 ,

Section 6.143 [MAX], page 118

6.149 MERGE — Merge variables

Description:

Select values from two arrays according to a logical mask. The result is equal to TSOURCE if MASK is .TRUE., or equal to FSOURCE if it is .FALSE..

Standard : F95 and later

Class:

Syntax :

Elemental function

RESULT = MERGE(TSOURCE, FSOURCE, MASK)

Arguments:

TSOURCE

FSOURCE

MASK

May be of any type.

Shall be of the same type and type parameters as TSOURCE.

Shall be of type LOGICAL(*).

Return value:

The result is of the same type and type parameters as TSOURCE.

6.150 MIN — Minimum value of an argument list

Description:

Returns the argument with the smallest (most negative) value.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = MIN(A1, A2 [, A3, ...])

Arguments:

A2, A3, ...

The type shall be INTEGER(*) or REAL(*).

An expression of the same type and kind as A1. (As a GNU extension, arguments of different kinds are permitted.)

122 The GNU Fortran Compiler

Return value:

The return value corresponds to the maximum value among the arguments, and has the same type and kind as the first argument.

Specific names:

Name

MIN0(I)

AMIN0(I)

MIN1(X)

AMIN1(X)

DMIN1(X)

Argument

REAL(4) X

REAL(8) X

Return type

REAL(4)

REAL(8)

Standard

INTEGER(4) I INTEGER(4)

F77 and later

INTEGER(4) I REAL(MIN(X))

F77 and later

REAL(*) X INT(MIN(X))

F77 and later

See also:

Section 6.152 [MINLOC], page 122

Section 6.153 [MINVAL], page 123

6.151 MINEXPONENT — Minimum exponent of a real kind

Description:

MINEXPONENT(X) returns the minimum exponent in the model of the type of X.

Standard : F95 and later

Class: Inquiry function

Syntax :

RESULT = MINEXPONENT(X)

Arguments:

X Shall be of type REAL.

Return value:

The return value is of type INTEGER and of the default integer kind.

Example: See MAXEXPONENT for an example.

6.152 MINLOC — Location of the minimum value within an array

Description:

Determines the location of the element in the array with the minimum value, or, if the DIM argument is supplied, determines the locations of the minimum element along each row of the array in the DIM direction. If MASK is present, only the elements for which MASK is .TRUE. are considered. If more than one element in the array has the minimum value, the location returned is that of the first such element in array element order. If the array has zero size, or all of the elements of MASK are .FALSE., then the result is an array of zeroes.

Similarly, if DIM is supplied and all of the elements of MASK along a given row are zero, the result value for that row is zero.

Standard : F95 and later

Class:

Syntax :

Transformational function

Chapter 6: Intrinsic Procedures 123

RESULT = MINLOC(ARRAY, DIM [, MASK])

RESULT = MINLOC(ARRAY [, MASK])

Arguments:

ARRAY

DIM

MASK

Shall be an array of type INTEGER(*),

REAL(*), or

CHARACTER(*).

(Optional) Shall be a scalar of type INTEGER(*), with a value between one and the rank of ARRAY, inclusive. It may not be an optional dummy argument.

Shall be an array of type LOGICAL(*), and conformable with

ARRAY.

Return value:

DIM dimension removed. If DIM is present and ARRAY has a rank of one, the result is a scalar. In all cases, the result is of default INTEGER type.

See also:

Section 6.150 [MIN], page 121

Section 6.153 [MINVAL], page 123

6.153 MINVAL — Minimum value of an array

Description:

Determines the minimum value of the elements in an array value, or, if the

DIM argument is supplied, determines the minimum value along each row of the array in the DIM direction. If MASK is present, only the elements for which MASK is .TRUE. are considered. If the array has zero size, or all of the elements of MASK are .FALSE., then the result is HUGE(ARRAY) if ARRAY is numeric, or a string of CHAR(255) characters if ARRAY is of character type.

Standard : F95 and later

Class: Transformational function

Syntax :

RESULT = MINVAL(ARRAY, DIM [, MASK])

RESULT = MINVAL(ARRAY [, MASK])

Arguments:

ARRAY

DIM

MASK

Shall be an array of type INTEGER(*),

REAL(*), or

CHARACTER(*).

(Optional) Shall be a scalar of type INTEGER(*), with a value between one and the rank of ARRAY, inclusive. It may not be an optional dummy argument.

Shall be an array of type LOGICAL(*), and conformable with

ARRAY.

Return value:

If DIM is absent, or if ARRAY has a rank of one, the result is a scalar. If DIM is present, the result is an array with a rank one less than the rank of ARRAY, and

124 The GNU Fortran Compiler a size corresponding to the size of ARRAY with the DIM dimension removed.

In all cases, the result is of the same type and kind as ARRAY.

See also:

Section 6.150 [MIN], page 121

Section 6.152 [MINLOC], page 122

6.154 MOD — Remainder function

Description:

MOD(A,P) computes the remainder of the division of A by P. It is calculated as

A - (INT(A/P) * P).

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = MOD(A, P)

Arguments:

Return value:

The kind of the return value is the result of cross-promoting the kinds of the arguments.

Example:

Shall be a scalar of type INTEGER or REAL

Shall be a scalar of the same type as A and not equal to zero program test_mod print *, mod(17,3) print *, mod(17.5,5.5) print *, mod(17.5d0,5.5) print *, mod(17.5,5.5d0) print *, mod(-17,3) print *, mod(-17.5,5.5) print *, mod(-17.5d0,5.5) print *, mod(-17.5,5.5d0) print *, mod(17,-3) print *, mod(17.5,-5.5) print *, mod(17.5d0,-5.5) print *, mod(17.5,-5.5d0) end program test_mod

Specific names:

Name

AMOD(A,P)

DMOD(A,P)

Arguments

REAL(4)

REAL(8)

Return type

REAL(4)

REAL(8)

Standard

F95 and later

6.155 MODULO — Modulo function

Description:

MODULO(A,P) computes the A modulo P.

Standard : F95 and later

Class: Elemental function

Chapter 6: Intrinsic Procedures 125

Syntax :

RESULT = MODULO(A, P)

Arguments:

Shall be a scalar of type INTEGER or REAL

Shall be a scalar of the same type and kind as A

Return value:

The type and kind of the result are those of the arguments.

If A and P are of type INTEGER:

MODULO(A,P) has the value R such that A=Q*P+R, where Q is an integer and R is between 0 (inclusive) and P (exclusive).

If A and P are of type REAL:

MODULO(A,P) has the value of A - FLOOR (A / P) * P.

In all cases, if P is zero the result is processor-dependent.

Example: program test_modulo print *, modulo(17,3) print *, modulo(17.5,5.5) print *, modulo(-17,3) print *, modulo(-17.5,5.5) print *, modulo(17,-3) print *, modulo(17.5,-5.5) end program

6.156 MOVE_ALLOC — Move allocation from one object to another

Description:

MOVE_ALLOC(SRC, DEST) moves the allocation from SRC to DEST. SRC will become deallocated in the process.

Standard : F2003 and later

Class: Subroutine

Syntax :

CALL MOVE_ALLOC(SRC, DEST)

Arguments:

SRC

DEST

ALLOCATABLE, INTENT(INOUT), may be of any type and kind.

ALLOCATABLE, INTENT(OUT), shall be of the same type, kind and rank as SRC

Return value:

None

Example: program test_move_alloc integer, allocatable :: a(:), b(:) allocate(a(3))

126 The GNU Fortran Compiler a = [ 1, 2, 3 ] call move_alloc(a, b) print *, allocated(a), allocated(b) print *, b end program test_move_alloc

6.157 MVBITS — Move bits from one integer to another

Description:

Moves LEN bits from positions FROMPOS through FROMPOS+LEN-1 of FROM to positions TOPOS through TOPOS+LEN-1 of TO. The portion of argument TO not affected by the movement of bits is unchanged. The values of FROMPOS+LEN-

1 and TOPOS+LEN-1 must be less than BIT_SIZE(FROM).

Standard : F95 and later

Class: Elemental subroutine

Syntax :

CALL MVBITS(FROM, FROMPOS, LEN, TO, TOPOS)

Arguments:

FROM

FROMPOS

LEN

TOPOS

The type shall be INTEGER(*).

The type shall be INTEGER(*), of the same kind as FROM.

The type shall be INTEGER(*).

See also:

Section 6.101 [IBCLR], page 96

Section 6.103 [IBSET], page 97 , Section 6.102

Section 6.37 [CEILING], page 58 ,

6.158 NEAREST — Nearest representable number

Description:

NEAREST(X, S) returns the processor-representable number nearest to X in the direction indicated by the sign of S.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = NEAREST(X, S)

Arguments:

Return value:

The return value is of the same type as X. If S is positive, NEAREST returns the processor-representable number greater than X and nearest to it. If S is negative, NEAREST returns the processor-representable number smaller than X and nearest to it.

Example:

Shall be of type REAL.

(Optional) shall be of type REAL and not equal to zero.

Chapter 6: Intrinsic Procedures 127 program test_nearest real :: x, y x = nearest(42.0, 1.0) y = nearest(42.0, -1.0) write (*,"(3(G20.15))") x, y, x - y end program test_nearest

6.159 NEW_LINE — New line character

Description:

NEW_LINE(C) returns the new-line character.

Standard : F2003 and later

Class: Inquiry function

Syntax :

RESULT = NEW_LINE(C)

Arguments:

C The argument shall be a scalar or array of the type

CHARACTER.

Return value:

Returns a CHARACTER scalar of length one with the new-line character of the same kind as parameter C.

Example: program newline implicit none write(*,’(A)’) ’This is record 1.’//NEW_LINE(’A’)//’This is record 2.’ end program newline

6.160 NINT — Nearest whole number

Description:

NINT(X) rounds its argument to the nearest whole number.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = NINT(X)

Arguments:

X The type of the argument shall be REAL.

Return value:

Returns A with the fractional portion of its magnitude eliminated by rounding to the nearest whole number and with its sign preserved, converted to an

INTEGER of the default kind.

Example: program test_nint real(4) x4 real(8) x8 x4 = 1.234E0_4

128 The GNU Fortran Compiler x8 = 4.321_8

print *, nint(x4), idnint(x8) end program test_nint

Specific names:

Name

IDNINT(X)

Argument

REAL(8)

Standard

F95 and later

See also:

Section 6.73 [FLOOR], page 81

6.161 NOT — Logical negation

Description:

NOT returns the bitwise boolean inverse of I.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = NOT(I)

Arguments:

I The type shall be INTEGER(*).

Return value:

The return type is INTEGER(*), of the same kind as the argument.

See also:

Section 6.102 [IBITS], page 97

Section 6.112

[IOR], page 102

Section 6.103 [IBSET], page 97

Section 6.101 [IBCLR], page 96

6.162 NULL — Function that returns an disassociated pointer

Description:

Returns a disassociated pointer.

If MOLD is present, a dissassociated pointer of the same type is returned, otherwise the type is determined by context.

In Fortran 95, MOLD is optional. Please note that F2003 includes cases where it is required.

Standard : F95 and later

Class: Transformational function

Syntax :

PTR => NULL([MOLD])

Arguments:

MOLD (Optional) shall be a pointer of any association status and of any type.

Return value:

A disassociated pointer.

Example:

REAL, POINTER, DIMENSION(:) :: VEC => NULL ()

See also:

Section 6.20 [ASSOCIATED], page 48

Chapter 6: Intrinsic Procedures 129

6.163 OR — Bitwise logical OR

Description:

Bitwise logical OR.

This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. For integer arguments, programmers should consider the use of the

Section 6.218 [UNPACK], page 159

intrinsic defined by the Fortran standard.

Standard : GNU extension

Class: Function

Syntax :

RESULT = OR(X, Y)

Arguments:

Return value:

The return type is either INTEGER(*) or LOGICAL after cross-promotion of the arguments.

Example:

The type shall be either INTEGER(*) or LOGICAL.

PROGRAM test_or

LOGICAL :: T = .TRUE., F = .FALSE.

INTEGER :: a, b

DATA a / Z’F’ /, b / Z’3’ /

WRITE (*,*) OR(T, T), OR(T, F), OR(F, T), OR(F, F)

WRITE (*,*) OR(a, b)

END PROGRAM

6.164 PACK — Pack an array into an array of rank one

Description:

Stores the elements of ARRAY in an array of rank one.

The beginning of the resulting array is made up of elements whose MASK equals

TRUE. Afterwards, positions are filled with elements taken from VECTOR.

Standard : F95 and later

Class: Transformational function

Syntax :

RESULT = PACK(ARRAY, MASK[,VECTOR]

Arguments:

ARRAY

MASK

Shall be an array of any type.

Shall be an array of type LOGICAL and of the same size as

ARRAY. Alternatively, it may be a LOGICAL scalar.

130 The GNU Fortran Compiler

VECTOR (Optional) shall be an array of the same type as ARRAY and of rank one. If present, the number of elements in VECTOR shall be equal to or greater than the number of true elements in MASK. If MASK is scalar, the number of elements in VEC-

TOR shall be equal to or greater than the number of elements in ARRAY.

Return value:

The result is an array of rank one and the same type as that of ARRAY. If

VECTOR is present, the result size is that of VECTOR, the number of TRUE values in MASK otherwise.

Example: Gathering nonzero elements from an array:

PROGRAM test_pack_1

INTEGER :: m(6) m = (/ 1, 0, 0, 0, 5, 0 /)

WRITE(*, FMT="(6(I0, ’ ’))") pack(m, m /= 0) ! "1 5"

END PROGRAM

Gathering nonzero elements from an array and appending elements from VEC-

TOR:

PROGRAM test_pack_2

INTEGER :: m(4) m = (/ 1, 0, 0, 2 /)

WRITE(*, FMT="(4(I0, ’ ’))") pack(m, m /= 0, (/ 0, 0, 3, 4 /)) ! "1 2 3 4"

END PROGRAM

See also:

6.165 PERROR — Print system error message

Description:

Prints (on the C stderr stream) a newline-terminated error message corresponding to the last system error. This is prefixed by STRING, a colon and a space. See perror(3).

Standard : GNU extension

Class: Subroutine

Syntax :

CALL PERROR(STRING)

Arguments:

STRING A scalar of default CHARACTER type.

See also:

Section 6.107 [IERRNO], page 99

6.166 PRECISION — Decimal precision of a real kind

Description:

PRECISION(X) returns the decimal precision in the model of the type of X.

Standard : F95 and later

Class: Inquiry function

Chapter 6: Intrinsic Procedures 131

Syntax :

RESULT = PRECISION(X)

Arguments:

X Shall be of type REAL or COMPLEX.

Return value:

The return value is of type INTEGER and of the default integer kind.

Example: program prec_and_range real(kind=4) :: x(2) complex(kind=8) :: y print *, precision(x), range(x) print *, precision(y), range(y) end program prec_and_range

6.167 PRESENT — Determine whether an optional dummy argument is specified

Description:

Determines whether an optional dummy argument is present.

Standard : F95 and later

Class: Inquiry function

Syntax :

RESULT = PRESENT(A)

Arguments:

A May be of any type and may be a pointer, scalar or array value, or a dummy procedure. It shall be the name of an optional dummy argument accessible within the current subroutine or function.

Return value:

Returns either TRUE if the optional argument A is present, or FALSE otherwise.

Example:

PROGRAM test_present

WRITE(*,*) f(), f(42)

CONTAINS

LOGICAL FUNCTION f(x)

! "F T"

INTEGER, INTENT(IN), OPTIONAL :: x f = PRESENT(x)

END FUNCTION

END PROGRAM

6.168 PRODUCT — Product of array elements

Description:

Multiplies the elements of ARRAY along dimension DIM if the corresponding element in MASK is TRUE.

Standard : F95 and later

132 The GNU Fortran Compiler

Class: Transformational function

Syntax :

RESULT = PRODUCT(ARRAY[, MASK]) RESULT = PRODUCT(ARRAY, DIM[, MASK])

Arguments:

ARRAY

DIM

MASK

Shall be an array of type

INTEGER(*), REAL(*) or

COMPLEX(*).

(Optional) shall be a scalar of type INTEGER with a value in the range from 1 to n, where n equals the rank of ARRAY.

(Optional) shall be of type LOGICAL and either be a scalar or an array of the same shape as ARRAY.

Return value:

The result is of the same type as ARRAY.

If DIM is absent, a scalar with the product of all elements in ARRAY is returned. Otherwise, an array of rank n-1, where n equals the rank of ARRAY, and a shape similar to that of ARRAY with dimension DIM dropped is returned.

Example:

PROGRAM test_product

INTEGER :: x(5) = (/ 1, 2, 3, 4 ,5 /) print *, PRODUCT(x) ! all elements, product = 120 print *, PRODUCT(x, MASK=MOD(x, 2)==1) ! odd elements, product = 15

END PROGRAM

See also:

Section 6.202 [SUM], page 151

6.169 RADIX — Base of a model number

Description:

RADIX(X) returns the base of the model representing the entity X.

Standard : F95 and later

Class: Inquiry function

Syntax :

RESULT = RADIX(X)

Arguments:

X Shall be of type INTEGER or REAL

Return value:

The return value is a scalar of type INTEGER and of the default integer kind.

Example: program test_radix print *, "The radix for the default integer kind is", radix(0) print *, "The radix for the default real kind is", radix(0.0) end program test_radix

Chapter 6: Intrinsic Procedures 133

6.170 RAN — Real pseudo-random number

Description:

For compatibility with HP FORTRAN 77/iX, the RAN intrinsic is provided as an alias for RAND. See

Section 6.171 [RAND], page 133

for complete documentation.

Standard : GNU extension

Class: Function

6.171 RAND — Real pseudo-random number

Description:

RAND(FLAG) returns a pseudo-random number from a uniform distribution between 0 and 1. If FLAG is 0, the next number in the current sequence is returned; if FLAG is 1, the generator is restarted by CALL SRAND(0); if FLAG has any other value, it is used as a new seed with SRAND.

This intrinsic routine is provided for backwards compatibility with GNU Fortran

77. It implements a simple modulo generator as provided by g77. For new code, one should consider the use of

Section 6.200 [SRAND], page 149

as it implements a superior algorithm.

Standard : GNU extension

Class: Function

Syntax :

RESULT = RAND(FLAG)

Arguments:

FLAG Shall be a scalar INTEGER of kind 4.

Return value:

The return value is of REAL type and the default kind.

Example: program test_rand integer,parameter :: seed = 86456 call srand(seed) print *, rand(), rand(), rand(), rand() print *, rand(seed), rand(), rand(), rand() end program test_rand

See also:

Section 6.173 [RANDOM SEED], page 134

6.172 RANDOM_NUMBER — Pseudo-random number

Description:

Returns a single pseudorandom number or an array of pseudorandom numbers from the uniform distribution over the range 0 ≤ x < 1.

134 The GNU Fortran Compiler

The runtime-library implements George Marsaglia’s KISS (Keep It Simple

Stupid) random number generator (RNG). This RNG combines:

1. The congruential generator x(n) = 69069 · x(n − 1) + 1327217885 with a period of 2

2. A 3-shift shift-register generator with a period of 2

− 1,

3. Two 16-bit multiply-with-carry generators with a period of

597273182964842497 > 2

The overall period exceeds 2

123

Please note, this RNG is thread safe if used within OpenMP directives, i. e. its state will be consistent while called from multiple threads. However, the KISS generator does not create random numbers in parallel from multiple sources, but in sequence from a single source. If an OpenMP-enabled application heavily relies on random numbers, one should consider employing a dedicated parallel random number generator instead.

Standard : F95 and later

Class:

Syntax :

Example:

Subroutine

RANDOM_NUMBER(HARVEST)

Arguments:

HARVEST Shall be a scalar or an array of type REAL(*).

program test_random_number

REAL :: r(5,5)

CALL init_random_seed()

CALL RANDOM_NUMBER(r) end program

! see example of RANDOM_SEED

See also:

6.173 RANDOM_SEED — Initialize a pseudo-random number sequence

Description:

Restarts or queries the state of the pseudorandom number generator used by

RANDOM_NUMBER.

If RANDOM_SEED is called without arguments, it is initialized to a default state.

The example below shows how to initialize the random seed based on the system’s time.

Standard : F95 and later

Class:

Syntax :

Subroutine

CALL RANDOM_SEED(SIZE, PUT, GET)

Arguments:

SIZE (Optional) Shall be a scalar and of type default INTEGER, with

INTENT(OUT). It specifies the minimum size of the arrays used with the PUT and GET arguments.

Chapter 6: Intrinsic Procedures 135

PUT

GET

(Optional) Shall be an array of type default INTEGER and rank one. It is INTENT(IN) and the size of the array must be larger than or equal to the number returned by the SIZE argument.

(Optional) Shall be an array of type default INTEGER and rank one. It is INTENT(OUT) and the size of the array must be larger than or equal to the number returned by the SIZE argument.

Example:

SUBROUTINE init_random_seed()

INTEGER :: i, n, clock

INTEGER, DIMENSION(:), ALLOCATABLE :: seed

CALL RANDOM_SEED(size = n)

ALLOCATE(seed(n))

CALL SYSTEM_CLOCK(COUNT=clock) seed = clock + 37 * (/ (i - 1, i = 1, n) /)

CALL RANDOM_SEED(PUT = seed)

DEALLOCATE(seed)

END SUBROUTINE

See also:

6.174 RANGE — Decimal exponent range of a real kind

Description:

RANGE(X) returns the decimal exponent range in the model of the type of X.

Standard : F95 and later

Class: Inquiry function

Syntax :

RESULT = RANGE(X)

Arguments:

X Shall be of type REAL or COMPLEX.

Return value:

The return value is of type INTEGER and of the default integer kind.

Example: See PRECISION for an example.

6.175 REAL — Convert to real type

Description:

REAL(X [, KIND]) converts its argument X to a real type. The REALPART(X) function is provided for compatibility with g77, and its use is strongly discouraged.

Standard : F77 and later

Class: Elemental function

136 The GNU Fortran Compiler

Syntax :

RESULT = REAL(X [, KIND])

RESULT = REALPART(Z)

Arguments:

KIND

Shall be INTEGER(*), REAL(*), or COMPLEX(*).

(Optional) An INTEGER(*) initialization expression indicating the kind parameter of the result.

Return value:

These functions return a REAL(*) variable or array under the following rules:

(A)

REAL(X) is converted to a default real type if X is an integer or real variable.

(B)

REAL(X) is converted to a real type with the kind type parameter of X if X is a complex variable.

(C)

REAL(X, KIND) is converted to a real type with kind type parameter

KIND if X is a complex, integer, or real variable.

Example: program test_real complex :: x = (1.0, 2.0) print *, real(x), real(x,8), realpart(x) end program test_real

See also:

Section 6.54 [DFLOAT], page 69 ,

Section 6.70

[FLOAT], page 79

6.176 RENAME — Rename a file

Description:

Renames a file from file PATH1 to PATH2. A null character (CHAR(0)) can be used to mark the end of the names in PATH1 and PATH2; otherwise, trailing blanks in the file names are ignored. If the STATUS argument is supplied, it contains 0 on success or a nonzero error code upon return; see rename(2).

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL RENAME(PATH1, PATH2 [, STATUS])

STATUS = RENAME(PATH1, PATH2)

Arguments:

PATH1

PATH2

STATUS

Shall be of default CHARACTER type.

(Optional) Shall be of default INTEGER type.

See also:

Section 6.129 [LINK], page 110

Chapter 6: Intrinsic Procedures 137

6.177 REPEAT — Repeated string concatenation

Description:

Concatenates NCOPIES copies of a string.

Standard : F95 and later

Class: Transformational function

Syntax :

RESULT = REPEAT(STRING, NCOPIES)

Arguments:

STRING

NCOPIES

Return value:

A new scalar of type CHARACTER built up from NCOPIES copies of STRING.

Example:

Shall be scalar and of type CHARACTER(*).

Shall be scalar and of type INTEGER(*).

program test_repeat write(*,*) repeat("x", 5) ! "xxxxx" end program

6.178 RESHAPE — Function to reshape an array

Description:

Reshapes SOURCE to correspond to SHAPE. If necessary, the new array may be padded with elements from PAD or permuted as defined by ORDER.

Standard : F95 and later

Class: Transformational function

Syntax :

RESULT = RESHAPE(SOURCE, SHAPE[, PAD, ORDER])

Arguments:

SOURCE

SHAPE

PAD

ORDER

Shall be an array of any type.

Shall be of type INTEGER and an array of rank one. Its values must be positive or zero.

(Optional) shall be an array of the same type as SOURCE.

(Optional) shall be of type INTEGER and an array of the same shape as SHAPE. Its values shall be a permutation of the numbers from 1 to n, where n is the size of SHAPE. If ORDER is absent, the natural ordering shall be assumed.

Return value:

The result is an array of shape SHAPE with the same type as SOURCE.

Example:

PROGRAM test_reshape

INTEGER, DIMENSION(4) :: x

WRITE(*,*) SHAPE(x)

WRITE(*,*) SHAPE(RESHAPE(x, (/2, 2/)))

END PROGRAM

! prints "4"

! prints "2 2"

See also:

Section 6.188 [SHAPE], page 142

138 The GNU Fortran Compiler

6.179 RRSPACING — Reciprocal of the relative spacing

Description:

RRSPACING(X) returns the reciprocal of the relative spacing of model numbers near X.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = RRSPACING(X)

Arguments:

X Shall be of type REAL.

Return value:

The return value is of the same type and kind as X. The value returned is equal to ABS(FRACTION(X)) * FLOAT(RADIX(X))**DIGITS(X).

See also:

Section 6.197 [SPACING], page 147

6.180 RSHIFT — Right shift bits

Description:

RSHIFT returns a value corresponding to I with all of the bits shifted right by

SHIFT places. If the absolute value of SHIFT is greater than BIT_SIZE(I), the value is undefined. Bits shifted out from the left end are lost; zeros are shifted in from the opposite end.

This function has been superseded by the ISHFT intrinsic, which is standard in

Fortran 95 and later.

Standard : GNU extension

Class: Elemental function

Syntax :

RESULT = RSHIFT(I, SHIFT)

Arguments:

SHIFT

The type shall be INTEGER(*).

Return value:

The return value is of type INTEGER(*) and of the same kind as I.

See also:

Section 6.117 [ISHFT], page 104 ,

Section 6.118 [ISHFTC], page 105

Section 6.138 [LSHIFT], page 115

6.181 SCALE — Scale a real value

Description:

SCALE(X,I) returns X * RADIX(X)**I.

Standard : F95 and later

Class: Elemental function

Chapter 6: Intrinsic Procedures 139

Syntax :

RESULT = SCALE(X, I)

Arguments:

The type of the argument shall be a REAL.

The type of the argument shall be a INTEGER.

Return value:

The return value is of the same type and kind as X. Its value is X * RADIX(X)**I.

Example: program test_scale real :: x = 178.1387e-4 integer :: i = 5 print *, scale(x,i), x*radix(x)**i end program test_scale

6.182 SCAN — Scan a string for the presence of a set of characters

Description:

Scans a STRING for any of the characters in a SET of characters.

If BACK is either absent or equals FALSE, this function returns the position of the leftmost character of STRING that is in SET. If BACK equals TRUE, the rightmost position is returned. If no character of SET is found in STRING, the result is zero.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = SCAN(STRING, SET[, BACK [, KIND]])

Arguments:

STRING

SET

BACK

KIND

Shall be of type CHARACTER(*).

(Optional) shall be of type LOGICAL.

(Optional) An INTEGER initialization expression indicating the kind parameter of the result.

Return value:

The return value is of type INTEGER and of kind KIND. If KIND is absent, the return value is of default integer kind.

Example:

PROGRAM test_scan

WRITE(*,*) SCAN("FORTRAN", "AO") ! 2, found ’O’

WRITE(*,*) SCAN("FORTRAN", "AO", .TRUE.) ! 6, found ’A’

WRITE(*,*) SCAN("FORTRAN", "C++") ! 0, found none

END PROGRAM

Section 6.219 [VERIFY], page 159

140 The GNU Fortran Compiler

6.183 SECNDS — Time function

Description:

SECNDS(X) gets the time in seconds from the real-time system clock. X is a reference time, also in seconds. If this is zero, the time in seconds from midnight is returned. This function is non-standard and its use is discouraged.

Standard : GNU extension

Class:

Syntax :

Function

RESULT = SECNDS (X)

Arguments:

Return value:

None

Shall be of type REAL(4).

Example: program test_secnds integer :: i real(4) :: t1, t2 print *, secnds (0.0) ! seconds since midnight t1 = secnds (0.0) ! reference time do i = 1, 10000000 ! do something end do t2 = secnds (t1) ! elapsed time print *, "Something took ", t2, " seconds." end program test_secnds

6.184 SECOND — CPU time function

Description:

Returns a REAL(4) value representing the elapsed CPU time in seconds. This provides the same functionality as the standard CPU_TIME intrinsic, and is only included for backwards compatibility.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL SECOND(TIME)

TIME = SECOND()

Arguments:

TIME Shall be of type REAL(4).

Return value:

In either syntax, TIME is set to the process’s current runtime in seconds.

See also:

Section 6.178 [RESHAPE], page 137

Chapter 6: Intrinsic Procedures 141

6.185 SELECTED_INT_KIND — Choose integer kind

Description:

SELECTED_INT_KIND(I) return the kind value of the smallest integer type that can represent all values ranging from −10

(exclusive) to 10

(exclusive). If there is no integer kind that accommodates this range, SELECTED_INT_KIND returns −1.

Standard : F95 and later

Class:

Syntax :

Example:

Transformational function

RESULT = SELECTED_INT_KIND(I)

Arguments:

I Shall be a scalar and of type INTEGER.

program large_integers integer,parameter :: k5 = selected_int_kind(5) integer,parameter :: k15 = selected_int_kind(15) integer(kind=k5) :: i5 integer(kind=k15) :: i15 print *, huge(i5), huge(i15)

! The following inequalities are always true print *, huge(i5) >= 10_k5**5-1 print *, huge(i15) >= 10_k15**15-1 end program large_integers

6.186 SELECTED_REAL_KIND — Choose real kind

Description:

SELECTED_REAL_KIND(P,R) return the kind value of a real data type with decimal precision greater of at least P digits and exponent range greater at least

Standard : F95 and later

Class:

Syntax :

Transformational function

RESULT = SELECTED_REAL_KIND(P, R)

Arguments:

(Optional) shall be a scalar and of type INTEGER.

At least one argument shall be present.

Return value:

SELECTED_REAL_KIND returns the value of the kind type parameter of a real data type with decimal precision of at least P digits and a decimal exponent range of at least R. If more than one real data type meet the criteria, the kind of the data type with the smallest decimal precision is returned. If no real data type matches the criteria, the result is

142 The GNU Fortran Compiler

-1 if the processor does not support a real data type with a precision greater than or equal to P

-2 if the processor does not support a real type with an exponent range greater than or equal to R

-3 if neither is supported.

Example: program real_kinds integer,parameter :: p6 = selected_real_kind(6) integer,parameter :: p10r100 = selected_real_kind(10,100) integer,parameter :: r400 = selected_real_kind(r=400) real(kind=p6) :: x real(kind=p10r100) :: y real(kind=r400) :: z print *, precision(x), range(x) print *, precision(y), range(y) print *, precision(z), range(z) end program real_kinds

6.187 SET_EXPONENT — Set the exponent of the model

Description:

SET_EXPONENT(X, I) returns the real number whose fractional part is that that of X and whose exponent part is I.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = SET_EXPONENT(X, I)

Arguments:

Shall be of type REAL.

Shall be of type INTEGER.

Return value:

The return value is of the same type and kind as X. The real number whose fractional part is that that of X and whose exponent part if I is returned; it is

FRACTION(X) * RADIX(X)**I.

Example:

PROGRAM test_setexp

REAL :: x = 178.1387e-4

INTEGER :: i = 17

PRINT *, SET_EXPONENT(x, i), FRACTION(x) * RADIX(x)**i

END PROGRAM

6.188 SHAPE — Determine the shape of an array

Description:

Determines the shape of an array.

Standard : F95 and later

Chapter 6: Intrinsic Procedures 143

Class: Inquiry function

Syntax :

RESULT = SHAPE(SOURCE)

Arguments:

SOURCE Shall be an array or scalar of any type. If SOURCE is a pointer it must be associated and allocatable arrays must be allocated.

Return value:

An INTEGER array of rank one with as many elements as SOURCE has dimensions. The elements of the resulting array correspond to the extend of SOURCE along the respective dimensions. If SOURCE is a scalar, the result is the rank one array of size zero.

Example:

PROGRAM test_shape

INTEGER, DIMENSION(-1:1, -1:2) :: A

WRITE(*,*) SHAPE(A) ! (/ 3, 4 /)

WRITE(*,*) SIZE(SHAPE(42))

END PROGRAM

! (/ /)

See also:

Section 6.193 [SIZE], page 145

6.189 SIGN — Sign copying function

Description:

SIGN(A,B) returns the value of A with the sign of B.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = SIGN(A, B)

Arguments:

Shall be of type INTEGER or REAL

Shall be of the same type and kind as A

Return value:

The kind of the return value is that of A and B. If B ≥ 0 then the result is

ABS(A), else it is -ABS(A).

Example: program test_sign print *, sign(-12,1) print *, sign(-12,0) print *, sign(-12,-1) print *, sign(-12.,1.) print *, sign(-12.,0.) print *, sign(-12.,-1.) end program test_sign

Specific names:

Name

ISIGN(A,P)

DSIGN(A,P)

Arguments

INTEGER(4)

REAL(8)

Return type

INTEGER(4)

REAL(8)

Standard f95, gnu f95, gnu

144 The GNU Fortran Compiler

6.190 SIGNAL — Signal handling subroutine (or function)

Description:

SIGNAL(NUMBER, HANDLER [, STATUS]) causes external subroutine HANDLER to be executed with a single integer argument when signal NUMBER occurs. If

HANDLER is an integer, it can be used to turn off handling of signal NUMBER or revert to its default action. See signal(2).

If SIGNAL is called as a subroutine and the STATUS argument is supplied, it is set to the value returned by signal(2).

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL SIGNAL(NUMBER, HANDLER [, STATUS])

STATUS = SIGNAL(NUMBER, HANDLER)

Arguments:

NUMBER

HANDLER

STATUS

Shall be a scalar integer, with INTENT(IN)

Signal handler (INTEGER FUNCTION or

SUBROUTINE) or dummy/global INTEGER scalar. INTEGER. It is INTENT(IN).

(Optional) STATUS shall be a scalar integer.

It has

INTENT(OUT).

Return value:

The SIGNAL function returns the value returned by signal(2).

Example: program test_signal intrinsic signal external handler_print call signal (12, handler_print) call signal (10, 1) call sleep (30) end program test_signal

6.191 SIN — Sine function

Description:

SIN(X) computes the sine of X.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = SIN(X)

Arguments:

X The type shall be REAL(*) or COMPLEX(*).

Return value:

The return value has same type and kind as X.

Chapter 6: Intrinsic Procedures 145

Example: program test_sin real :: x = 0.0

x = sin(x) end program test_sin

Specific names:

Name

DSIN(X)

CSIN(X)

ZSIN(X)

CDSIN(X)

Argument

REAL(8) X

Return type

REAL(8)

COMPLEX(4) X COMPLEX(4)

COMPLEX(8) X COMPLEX(8)

See also:

Section 6.18 [ASIN], page 47

6.192 SINH — Hyperbolic sine function

Description:

SINH(X) computes the hyperbolic sine of X.

Standard : F95 and later

Class:

Syntax :

Elemental function

RESULT = SINH(X)

Arguments:

X The type shall be REAL(*).

Return value:

The return value is of type REAL(*).

Example: program test_sinh real(8) :: x = - 1.0_8

x = sinh(x) end program test_sinh

Specific names:

Name

DSINH(X)

Argument

REAL(8) X

See also:

Section 6.19 [ASINH], page 48

Return type

REAL(8)

Standard f95, gnu f95, gnu f95, gnu f95, gnu

Standard

F95 and later

6.193 SIZE — Determine the size of an array

Description:

Determine the extent of ARRAY along a specified dimension DIM, or the total number of elements in ARRAY if DIM is absent.

Standard : F95 and later

Class: Inquiry function

Syntax :

RESULT = SIZE(ARRAY[, DIM [, KIND]])

146 The GNU Fortran Compiler

Arguments:

ARRAY

DIM

KIND

Shall be an array of any type. If ARRAY is a pointer it must be associated and allocatable arrays must be allocated.

(Optional) shall be a scalar of type INTEGER and its value shall be in the range from 1 to n, where n equals the rank of

ARRAY.

(Optional) An INTEGER initialization expression indicating the kind parameter of the result.

Return value:

The return value is of type INTEGER and of kind KIND. If KIND is absent, the return value is of default integer kind.

Example:

PROGRAM test_size

WRITE(*,*) SIZE((/ 1, 2 /))

END PROGRAM

! 2

See also:

Section 6.188 [SHAPE], page 142

Section 6.178 [RESHAPE], page 137

6.194 SIZEOF — Size in bytes of an expression

Description:

SIZEOF(X) calculates the number of bytes of storage the expression X occupies.

Standard : GNU extension

Class: Intrinsic function

Syntax :

N = SIZEOF(X)

Arguments:

X The argument shall be of any type, rank or shape.

Return value:

The return value is of type integer and of the system-dependent kind C SIZE T

(from the ISO C BINDING module). Its value is the number of bytes occupied by the argument. If the argument has the POINTER attribute, the number of bytes of the storage area pointed to is returned. If the argument is of a derived type with POINTER or ALLOCATABLE components, the return value doesn’t account for the sizes of the data pointed to by these components.

Example: integer :: i real :: r, s(5) print *, (sizeof(s)/sizeof(r) == 5) end

The example will print .TRUE. unless you are using a platform where default

REAL variables are unusually padded.

Chapter 6: Intrinsic Procedures 147

6.195 SLEEP — Sleep for the specified number of seconds

Description:

Calling this subroutine causes the process to pause for SECONDS seconds.

Standard : GNU extension

Class: Subroutine

Syntax :

Example:

CALL SLEEP(SECONDS)

Arguments:

SECONDS The type shall be of default INTEGER.

program test_sleep call sleep(5) end

6.196 SNGL — Convert double precision real to default real

Description:

SNGL(A) converts the double precision real A to a default real value. This is an archaic form of REAL that is specific to one type for A.

Standard : F77 and later

Class:

Syntax :

Elemental function

RESULT = SNGL(A)

Arguments:

A The type shall be a double precision REAL.

Return value:

The return value is of type default REAL.

See also:

Section 6.179 [RRSPACING], page 138

6.197 SPACING — Smallest distance between two numbers of a given type

Description:

Determines the distance between the argument X and the nearest adjacent number of the same type.

Standard : F95 and later

Class: Elemental function

Syntax :

RESULT = SPACING(X)

Arguments:

X Shall be of type REAL(*).

Return value:

The result is of the same type as the input argument X.

148 The GNU Fortran Compiler

Example:

PROGRAM test_spacing

INTEGER, PARAMETER :: SGL = SELECTED_REAL_KIND(p=6, r=37)

INTEGER, PARAMETER :: DBL = SELECTED_REAL_KIND(p=13, r=200)

WRITE(*,*) spacing(1.0_SGL)

WRITE(*,*) spacing(1.0_DBL)

END PROGRAM

See also:

! "1.1920929E-07" on i686

! "2.220446049250313E-016" on i686

6.198 SPREAD — Add a dimension to an array

Description:

Replicates a SOURCE array NCOPIES times along a specified dimension DIM.

Standard : F95 and later

Class:

Syntax :

Transformational function

RESULT = SPREAD(SOURCE, DIM, NCOPIES)

Arguments:

SOURCE

DIM

Shall be a scalar or an array of any type and a rank less than seven.

Shall be a scalar of type INTEGER with a value in the range from 1 to n+1, where n equals the rank of SOURCE.

Shall be a scalar of type INTEGER.

NCOPIES

Return value:

The result is an array of the same type as SOURCE and has rank n+1 where n equals the rank of SOURCE.

Example:

PROGRAM test_spread

INTEGER :: a = 1, b(2) = (/ 1, 2 /)

WRITE(*,*) SPREAD(A, 1, 2)

WRITE(*,*) SPREAD(B, 1, 2)

END PROGRAM

! "1 1"

! "1 1 2 2"

See also:

Section 6.218 [UNPACK], page 159

6.199 SQRT — Square-root function

Description:

SQRT(X) computes the square root of X.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = SQRT(X)

Arguments:

X The type shall be REAL(*) or COMPLEX(*).

Chapter 6: Intrinsic Procedures 149

Return value:

The return value is of type REAL(*) or COMPLEX(*). The kind type parameter is the same as X.

Example: program test_sqrt real(8) :: x = 2.0_8

complex :: z = (1.0, 2.0) x = sqrt(x) z = sqrt(z) end program test_sqrt

Specific names:

Name

DSQRT(X)

CSQRT(X)

ZSQRT(X)

CDSQRT(X)

Argument Return type

REAL(8) X REAL(8)

COMPLEX(4) X COMPLEX(4)

COMPLEX(8) X COMPLEX(8)

Standard

F95 and later

GNU extension

6.200 SRAND — Reinitialize the random number generator

Description:

SRAND reinitializes the pseudo-random number generator called by RAND and

IRAND. The new seed used by the generator is specified by the required argument

SEED.

Standard : GNU extension

Class: Subroutine

Syntax :

CALL SRAND(SEED)

Arguments:

SEED

Return value:

Does not return.

Shall be a scalar INTEGER(kind=4).

Example: See RAND and IRAND for examples.

Notes: The Fortran 2003 standard specifies the intrinsic RANDOM_SEED to initialize the pseudo-random numbers generator and RANDOM_NUMBER to generate pseudorandom numbers. Please note that in GNU Fortran, these two sets of intrinsics

(RAND, IRAND and SRAND on the one hand, RANDOM_NUMBER and RANDOM_SEED on the other hand) access two independent pseudo-random number generators.

See also:

Section 6.171 [RAND], page 133

Section 6.173 [RANDOM SEED], page 134

Section 6.168 [PRODUCT], page 131

6.201 STAT — Get file status

Description:

This function returns information about a file. No permissions are required on the file itself, but execute (search) permission is required on all of the directories in path that lead to the file.

150 The GNU Fortran Compiler

The elements that are obtained and stored in the array BUFF: buff(1) buff(2) buff(3) buff(4) buff(5) buff(6) buff(7) buff(8) buff(9) buff(10) buff(11) buff(12) buff(13)

Device ID

Inode number

File mode

Number of links

Owner’s uid

Owner’s gid

ID of device containing directory entry for file (0 if not available)

File size (bytes)

Last access time

Last modification time

Last file status change time

Preferred I/O block size (-1 if not available)

Number of blocks allocated (-1 if not available)

Not all these elements are relevant on all systems. If an element is not relevant, it is returned as 0.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL STAT(FILE,BUFF[,STATUS])

Arguments:

FILE

BUFF

STATUS

The type shall be CHARACTER(*), a valid path within the file system.

The type shall be INTEGER(4), DIMENSION(13).

(Optional) status flag of type INTEGER(4). Returns 0 on success and a system specific error code otherwise.

Example:

PROGRAM test_stat

INTEGER, DIMENSION(13) :: buff

INTEGER :: status

CALL STAT("/etc/passwd", buff, status)

IF (status == 0) THEN

WRITE (*, FMT="(’Device ID:’,

WRITE (*, FMT="(’Inode number:’,

WRITE (*, FMT="(’File mode (octal):’,

WRITE (*, FMT="(’Number of links:’,

WRITE (*, FMT="(’Owner’’s uid:’,

WRITE (*, FMT="(’Owner’’s gid:’,

WRITE (*, FMT="(’Device where located:’,

WRITE (*, FMT="(’File size:’,

T30, I19)") buff(1)

T30, I19)") buff(2)

T30, O19)") buff(3)

T30, I19)") buff(4)

T30, I19)") buff(5)

T30, I19)") buff(6)

T30, I19)") buff(7)

T30, I19)") buff(8)

WRITE (*, FMT="(’Last access time:’, T30, A19)") CTIME(buff(9))

WRITE (*, FMT="(’Last modification time’, T30, A19)") CTIME(buff(10))

WRITE (*, FMT="(’Last status change time:’, T30, A19)") CTIME(buff(11))

Chapter 6: Intrinsic Procedures 151

WRITE (*, FMT="(’Preferred block size:’, T30, I19)") buff(12)

WRITE (*, FMT="(’No. of blocks allocated:’, T30, I19)") buff(13)

END IF

END PROGRAM

6.202 SUM — Sum of array elements

Description:

Adds the elements of ARRAY along dimension DIM if the corresponding element in MASK is TRUE.

Standard : F95 and later

Class: Transformational function

Syntax :

RESULT = SUM(ARRAY[, MASK]) RESULT = SUM(ARRAY, DIM[, MASK])

Arguments:

ARRAY

DIM

MASK

Shall be an array of type

INTEGER(*), REAL(*) or

COMPLEX(*).

(Optional) shall be a scalar of type INTEGER with a value in the range from 1 to n, where n equals the rank of ARRAY.

(Optional) shall be of type LOGICAL and either be a scalar or an array of the same shape as ARRAY.

Return value:

The result is of the same type as ARRAY.

If DIM is absent, a scalar with the sum of all elements in ARRAY is returned.

Otherwise, an array of rank n-1, where n equals the rank of ARRAY,and a shape similar to that of ARRAY with dimension DIM dropped is returned.

Example:

PROGRAM test_sum

INTEGER :: x(5) = (/ 1, 2, 3, 4 ,5 /) print *, SUM(x) print *, SUM(x, MASK=MOD(x, 2)==1)

END PROGRAM

! all elements, sum = 15

! odd elements, sum = 9

See also:

6.203 SYMLNK — Create a symbolic link

Description:

Makes a symbolic link from file PATH1 to PATH2. A null character (CHAR(0)) can be used to mark the end of the names in PATH1 and PATH2; otherwise, trailing blanks in the file names are ignored. If the STATUS argument is supplied, it contains 0 on success or a nonzero error code upon return; see symlink(2). If the system does not supply symlink(2), ENOSYS is returned.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

152 The GNU Fortran Compiler

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL SYMLNK(PATH1, PATH2 [, STATUS])

STATUS = SYMLNK(PATH1, PATH2)

Arguments:

PATH1

PATH2

STATUS

Shall be of default CHARACTER type.

(Optional) Shall be of default INTEGER type.

See also:

Section 6.129 [LINK], page 110

Section 6.217 [UNLINK], page 158

6.204 SYSTEM — Execute a shell command

Description:

Passes the command COMMAND to a shell (see system(3)). If argument

STATUS is present, it contains the value returned by system(3), which is presumably 0 if the shell command succeeded. Note that which shell is used to invoke the command is system-dependent and environment-dependent.

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Standard : GNU extension

Class:

Syntax :

Subroutine, function

Arguments:

COMMAND Shall be of default CHARACTER type.

STATUS (Optional) Shall be of default INTEGER type.

See also:

CALL SYSTEM(COMMAND [, STATUS])

STATUS = SYSTEM(COMMAND)

6.205 SYSTEM_CLOCK — Time function

Description:

Determines the COUNT of milliseconds of wall clock time since the Epoch

(00:00:00 UTC, January 1, 1970) modulo COUNT MAX, COUNT RATE determines the number of clock ticks per second.

COUNT RATE and

COUNT MAX are constant and specific to gfortran.

If there is no clock, COUNT is set to -HUGE(COUNT), and COUNT RATE and

COUNT MAX are set to zero

Standard : F95 and later

Class: Subroutine

Chapter 6: Intrinsic Procedures 153

Syntax :

CALL SYSTEM_CLOCK([COUNT, COUNT_RATE, COUNT_MAX])

Arguments:

COUNT (Optional) shall be a scalar of type default INTEGER with

INTENT(OUT).

COUNT RATE(Optional) shall be a scalar of type default INTEGER with

INTENT(OUT).

COUNT MAX (Optional) shall be a scalar of type default INTEGER with

INTENT(OUT).

Example:

PROGRAM test_system_clock

INTEGER :: count, count_rate, count_max

CALL SYSTEM_CLOCK(count, count_rate, count_max)

WRITE(*,*) count, count_rate, count_max

END PROGRAM

See also:

Section 6.51 [DATE AND TIME], page 67 ,

Section 6.21 [ATAN], page 49

6.206 TAN — Tangent function

Description:

TAN(X) computes the tangent of X.

Standard : F77 and later

Class: Elemental function

Syntax :

RESULT = TAN(X)

Arguments:

X The type shall be REAL(*).

Return value:

The return value is of type REAL(*). The kind type parameter is the same as

Example: program test_tan real(8) :: x = 0.165_8

x = tan(x) end program test_tan

Specific names:

Name

DTAN(X)

Argument

REAL(8) X

See also:

Return type

REAL(8)

Standard

F95 and later

6.207 TANH — Hyperbolic tangent function

Description:

TANH(X) computes the hyperbolic tangent of X.

154 The GNU Fortran Compiler

Standard : F77 and later

Class:

Syntax :

Elemental function

X = TANH(X)

Arguments:

X The type shall be REAL(*).

Return value:

The return value is of type REAL(*) and lies in the range −1 ≤ tanh(x) ≤ 1.

Example: program test_tanh real(8) :: x = 2.1_8

x = tanh(x) end program test_tanh

Specific names:

Name

DTANH(X)

Argument

REAL(8) X

See also:

Section 6.23 [ATANH], page 50

Return type

REAL(8)

Standard

F95 and later

6.208 TIME — Time function

Description:

Returns the current time encoded as an integer (in the manner of the UNIX function time(3)). This value is suitable for passing to CTIME(), GMTIME(), and LTIME().

See

Section 6.209 [TIME8], page 155 , for information on a similar intrinsic that

might be portable to more GNU Fortran implementations, though to fewer

Fortran compilers.

Standard : GNU extension

Class: Function

Syntax :

RESULT = TIME()

Return value:

The return value is a scalar of type INTEGER(4).

See also:

Section 6.147 [MCLOCK], page 120 ,

Chapter 6: Intrinsic Procedures 155

6.209 TIME8 — Time function (64-bit)

Description:

Returns the current time encoded as an integer (in the manner of the UNIX function time(3)). This value is suitable for passing to CTIME(), GMTIME(), and LTIME().

Warning: this intrinsic does not increase the range of the timing values over that returned by time(3). On a system with a 32-bit time(3), TIME8() will return a 32-bit value, even though it is converted to a 64-bit INTEGER(8) value.

That means overflows of the 32-bit value can still occur. Therefore, the values returned by this intrinsic might be or become negative or numerically less than previous values during a single run of the compiled program.

Standard : GNU extension

Class: Function

Syntax :

RESULT = TIME8()

Return value:

The return value is a scalar of type INTEGER(8).

See also:

Section 6.148 [MCLOCK8], page 120 ,

Section 6.208 [TIME], page 154

6.210 TINY — Smallest positive number of a real kind

Description:

TINY(X) returns the smallest positive (non zero) number in the model of the type of X.

Standard : F95 and later

Class: Inquiry function

Syntax :

RESULT = TINY(X)

Arguments:

X Shall be of type REAL.

Return value:

The return value is of the same type and kind as X

Example: See HUGE for an example.

6.211 TRANSFER — Transfer bit patterns

Description:

Interprets the bitwise representation of SOURCE in memory as if it is the representation of a variable or array of the same type and type parameters as

MOLD.

This is approximately equivalent to the C concept of casting one type to another.

156 The GNU Fortran Compiler

Standard : F95 and later

Class:

Syntax :

Transformational function

RESULT = TRANSFER(SOURCE, MOLD[, SIZE])

Arguments:

SOURCE

MOLD

SIZE

Shall be a scalar or an array of any type.

(Optional) shall be a scalar of type INTEGER.

Return value:

The result has the same type as MOLD, with the bit level representation of

SOURCE. If SIZE is present, the result is a one-dimensional array of length

SIZE. If SIZE is absent but MOLD is an array (of any size or shape), the result is a one- dimensional array of the minimum length needed to contain the entirety of the bitwise representation of SOURCE. If SIZE is absent and

MOLD is a scalar, the result is a scalar.

If the bitwise representation of the result is longer than that of SOURCE, then the leading bits of the result correspond to those of SOURCE and any trailing bits are filled arbitrarily.

When the resulting bit representation does not correspond to a valid representation of a variable of the same type as MOLD, the results are undefined, and subsequent operations on the result cannot be guaranteed to produce sensible behavior. For example, it is possible to create LOGICAL variables for which VAR and .NOT.VAR both appear to be true.

Example:

PROGRAM test_transfer integer :: x = 2143289344 print *, transfer(x, 1.0)

END PROGRAM

! prints "NaN" on i686

6.212 TRANSPOSE — Transpose an array of rank two

Description:

Transpose an array of rank two. Element (i, j) of the result has the value

MATRIX(j, i), for all i, j.

Standard : F95 and later

Class: Transformational function

Syntax :

RESULT = TRANSPOSE(MATRIX)

Arguments:

MATRIX Shall be an array of any type and have a rank of two.

Return value:

The result has the the same type as MATRIX, and has shape (/ m, n /) if

MATRIX has shape (/ n, m /).

Chapter 6: Intrinsic Procedures 157

6.213 TRIM — Remove trailing blank characters of a string

Description:

Removes trailing blank characters of a string.

Standard : F95 and later

Class: Transformational function

Syntax :

RESULT = TRIM(STRING)

Arguments:

STRING Shall be a scalar of type CHARACTER(*).

Return value:

A scalar of type CHARACTER(*) which length is that of STRING less the number of trailing blanks.

Example:

PROGRAM test_trim

CHARACTER(len=10), PARAMETER :: s = "GFORTRAN "

WRITE(*,*) LEN(s), LEN(TRIM(s)) ! "10 8", with/without trailing blanks

END PROGRAM

See also:

Section 6.9 [ADJUSTR], page 41

6.214 TTYNAM — Get the name of a terminal device.

Description:

Get the name of a terminal device. For more information, see ttyname(3).

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL TTYNAM(UNIT, NAME)

NAME = TTYNAM(UNIT)

Arguments:

UNIT

NAME

Shall be a scalar INTEGER(*).

Shall be of type CHARACTER(*).

Example:

PROGRAM test_ttynam

INTEGER :: unit

DO unit = 1, 10

IF (isatty(unit=unit)) write(*,*) ttynam(unit)

END DO

END PROGRAM

See also:

Section 6.116 [ISATTY], page 104

158 The GNU Fortran Compiler

6.215 UBOUND — Upper dimension bounds of an array

Description:

Returns the upper bounds of an array, or a single upper bound along the DIM dimension.

Standard : F95 and later

Class: Inquiry function

Syntax :

RESULT = UBOUND(ARRAY [, DIM [, KIND]])

Arguments:

ARRAY

DIM

KIND

Shall be an array, of any type.

(Optional) Shall be a scalar INTEGER(*).

(Optional) An INTEGER initialization expression indicating the kind parameter of the result.

Return value:

The return value is of type INTEGER and of kind KIND. If KIND is absent, the return value is of default integer kind. If DIM is absent, the result is an array of the upper bounds of ARRAY. If DIM is present, the result is a scalar corresponding to the upper bound of the array along that dimension. If ARRAY is an expression rather than a whole array or array structure component, or if it has a zero extent along the relevant dimension, the upper bound is taken to be the number of elements along the relevant dimension.

See also:

Section 6.123 [LBOUND], page 107

6.216 UMASK — Set the file creation mask

Description:

Sets the file creation mask to MASK and returns the old value in argument

OLD if it is supplied. See umask(2).

Standard : GNU extension

Class: Subroutine

Syntax :

CALL UMASK(MASK [, OLD])

Arguments:

MASK

Shall be a scalar of type INTEGER(*).

(Optional) Shall be a scalar of type INTEGER(*).

6.217 UNLINK — Remove a file from the file system

Description:

Unlinks the file PATH. A null character (CHAR(0)) can be used to mark the end of the name in PATH ; otherwise, trailing blanks in the file name are ignored. If the STATUS argument is supplied, it contains 0 on success or a nonzero error code upon return; see unlink(2).

This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.

Chapter 6: Intrinsic Procedures 159

Standard : GNU extension

Class: Subroutine, function

Syntax :

CALL UNLINK(PATH [, STATUS])

STATUS = UNLINK(PATH)

Arguments:

PATH

STATUS

Shall be of default CHARACTER type.

(Optional) Shall be of default INTEGER type.

See also:

Section 6.129 [LINK], page 110

Section 6.203 [SYMLNK], page 151

6.218 UNPACK — Unpack an array of rank one into an array

Description:

Store the elements of VECTOR in an array of higher rank.

Standard : F95 and later

Class:

Syntax :

Transformational function

RESULT = UNPACK(VECTOR, MASK, FIELD)

Arguments:

VECTOR

MASK

FIELD

Shall be an array of any type and rank one. It shall have at least as many elements as MASK has TRUE values.

Shall be an array of type LOGICAL.

Shall be of the sam type as VECTOR and have the same shape as MASK.

Return value:

The resulting array corresponds to FIELD with TRUE elements of MASK replaced by values from VECTOR in array element order.

Example:

PROGRAM test_unpack integer :: vector(2) = (/1,1/) logical :: mask(4) = (/ .TRUE., .FALSE., .FALSE., .TRUE. /) integer :: field(2,2) = 0, unity(2,2)

! result: unity matrix unity = unpack(vector, reshape(mask, (/2,2/)), field)

END PROGRAM

See also:

Section 6.164 [PACK], page 129

Section 6.198 [SPREAD], page 148

6.219 VERIFY — Scan a string for the absence of a set of characters

Description:

Verifies that all the characters in a SET are present in a STRING.

If BACK is either absent or equals FALSE, this function returns the position of the leftmost character of STRING that is not in SET. If BACK equals TRUE, the

160 The GNU Fortran Compiler rightmost position is returned. If all characters of SET are found in STRING, the result is zero.

Standard : F95 and later

Class:

Syntax :

Elemental function

RESULT = VERIFY(STRING, SET[, BACK [, KIND]])

Arguments:

STRING

SET

BACK

KIND

Shall be of type CHARACTER(*).

(Optional) shall be of type LOGICAL.

(Optional) An INTEGER initialization expression indicating the kind parameter of the result.

Return value:

The return value is of type INTEGER and of kind KIND. If KIND is absent, the return value is of default integer kind.

Example:

PROGRAM test_verify

WRITE(*,*) VERIFY("FORTRAN", "AO")

WRITE(*,*) VERIFY("FORTRAN", "FOO")

WRITE(*,*) VERIFY("FORTRAN", "C++")

! 1, found ’F’

! 3, found ’R’

! 1, found ’F’

WRITE(*,*) VERIFY("FORTRAN", "C++", .TRUE.) ! 7, found ’N’

WRITE(*,*) VERIFY("FORTRAN", "FORTRAN")

END PROGRAM

! 0’ found none

See also:

Section 6.182 [SCAN], page 139 ,

Section 6.108 [INDEX intrinsic], page 100

6.220 XOR — Bitwise logical exclusive OR

Description:

Bitwise logical exclusive or.

This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. For integer arguments, programmers should consider the use of the

intrinsic defined by the Fortran standard.

Standard : GNU extension

Class:

Syntax :

Function

RESULT = XOR(X, Y)

Arguments:

Return value:

The return type is either INTEGER(*) or LOGICAL after cross-promotion of the arguments.

Example:

The type shall be either INTEGER(*) or LOGICAL.

Chapter 6: Intrinsic Procedures

PROGRAM test_xor

LOGICAL :: T = .TRUE., F = .FALSE.

INTEGER :: a, b

DATA a / Z’F’ /, b / Z’3’ /

WRITE (*,*) XOR(T, T), XOR(T, F), XOR(F, T), XOR(F, F)

WRITE (*,*) XOR(a, b)

END PROGRAM

7 Intrinsic Modules

7.1 ISO_FORTRAN_ENV

Standard : Fortran 2003

The ISO_FORTRAN_ENV module provides the following scalar default-integer named constants:

CHARACTER_STORAGE_SIZE:

Size in bits of the character storage unit.

ERROR_UNIT:

Indentifies the preconnected unit used for error reporting.

FILE_STORAGE_SIZE:

Size in bits of the file-storage unit.

INPUT_UNIT:

Indentifies the preconnected unit indentified by the asterisk (*) in READ statement.

IOSTAT_END:

The value assigned to the variable passed to the IOSTAT= specifier of an input/output statement if an end-of-file condition occurred.

IOSTAT_EOR:

The value assigned to the variable passed to the IOSTAT= specifier of an input/output statement if an end-of-record condition occurred.

NUMERIC_STORAGE_SIZE:

The size in bits of the numeric storage unit.

OUTPUT_UNIT:

Indentifies the preconnected unit indentified by the asterisk (*) in WRITE statement.

7.2 ISO_C_BINDING

Standard : Fortran 2003

The following intrinsic procedures are provided by the module; their definition can be found in the section Intrinsic Procedures of this manual.

C_ASSOCIATED

C_F_POINTER

C_F_PROCPOINTER

C_FUNLOC

C_LOC

The ISO_C_BINDING module provides the following named constants of the type integer, which can be used as KIND type parameter. Note that GNU Fortran currently does not support the C_INT_FAST... KIND type parameters (marked by an asterix (*) in the list

164 The GNU Fortran Compiler below). The C_INT_FAST... parameters have therefore the value −2 and cannot be used as KIND type parameter of the INTEGER type.

Fortran Type Named constant

INTEGER C_INT

INTEGER

C_SHORT

C_LONG

C_LONG_LONG

C_SIGNED_CHAR

C_SIZE_T

INTEGER

C_INT8_T

C_INT16_T

C_INT32_T

C_INT64_T

C_INT_LEAST8_T

C_INT_LEAST16_T

C_INT_LEAST32_T

C_INT_LEAST64_T

C_INT_FAST8_T*

C_INT_FAST16_T*

C_INT_FAST32_T*

C_INT_FAST64_T*

C_INTMAX_T

C_INTPTR_T

REAL

COMPLEX

LOGICAL

CHARACTER

C_FLOAT

C_DOUBLE

C_LONG_DOUBLE

C_FLOAT_COMPLEX

C_DOUBLE_COMPLEX

C_LONG_DOUBLE_COMPLEX

C_BOOL

C_CHAR

Additionally, the following (CHARACTER(KIND=C_CHAR) are defined.

C type int short int long int long long int signed char/unsigned char size_t int8_t int16_t int32_t int64_t int_least8_t int_least16_t int_least32_t int_least64_t int_fast8_t int_fast16_t int_fast32_t int_fast64_t intmax_t intptr_t float double long double float _Complex double _Complex long double _Complex

_Bool char

Name

C_NULL_CHAR

C_ALERT

C_BACKSPACE

C_FORM_FEED

C_NEW_LINE

C_CARRIAGE_

RETURN

C definition null character alert backspace form feed new line carriage return

C_HORIZONTAL_

TAB horizontal tab

C_VERTICAL_TAB vertical tab

Value

’\0’

’\a’

’\b’

’\f’

’\n’

’\r’

’\t’

’\v’

Chapter 7: Intrinsic Modules 165

7.3 OpenMP Modules OMP_LIB and OMP_LIB_KINDS

Standard : OpenMP Application Program Interface v2.5

The OpenMP Fortran runtime library routines are provided both in a form of two Fortran

90 modules, named OMP_LIB and OMP_LIB_KINDS, and in a form of a Fortran include file named ‘omp_lib.h’. The procedures provided by OMP_LIB can be found in the Section

“Introduction” in GNU OpenMP runtime library manual, the named constants defined in the OMP_LIB_KINDS module are listed below.

For details refer to the actual OpenMP Application Program Interface v2.5

OMP_LIB_KINDS provides the following scalar default-integer named constants: omp_integer_kind omp_logical_kind omp_lock_kind omp_nest_lock_kind

Contributing 167

Contributing

Free software is only possible if people contribute to efforts to create it. We’re always in need of more people helping out with ideas and comments, writing documentation and contributing code.

If you want to contribute to GNU Fortran, have a look at the long lists of projects you can take on. Some of these projects are small, some of them are large; some are completely orthogonal to the rest of what is happening on GNU Fortran, but others are “mainstream” projects in need of enthusiastic hackers. All of these projects are important! We’ll eventually get around to the things here, but they are also things doable by someone who is willing and able.

Contributors to GNU Fortran

Most of the parser was hand-crafted by Andy Vaught, who is also the initiator of the whole project. Thanks Andy! Most of the interface with GCC was written by Paul Brook.

The following individuals have contributed code and/or ideas and significant help to the

GNU Fortran project (in alphabetical order):

− Janne Blomqvist

− Steven Bosscher

− Paul Brook

− Tobias Burnus

− Fran¸cois-Xavier Coudert

− Bud Davis

− Jerry DeLisle

− Erik Edelmann

− Bernhard Fischer

− Daniel Franke

− Richard Guenther

− Richard Henderson

− Katherine Holcomb

− Jakub Jelinek

− Niels Kristian Bech Jensen

− Steven Johnson

− Steven G. Kargl

− Thomas Koenig

− Asher Langton

− H. J. Lu

− Toon Moene

− Brooks Moses

− Andrew Pinski

− Tim Prince

168 The GNU Fortran Compiler

− Christopher D. Rickett

− Richard Sandiford

− Roger Sayle

− Paul Thomas

− Andy Vaught

− Feng Wang

− Janus Weil

The following people have contributed bug reports, smaller or larger patches, and much needed feedback and encouragement for the GNU Fortran project:

− Bill Clodius

− Kate Hedstrom

− Erik Schnetter

Many other individuals have helped debug, test and improve the GNU Fortran compiler over the past few years, and we welcome you to do the same! If you already have done so, and you would like to see your name listed in the list above, please contact us.

Projects

Help build the test suite

Solicit more code for donation to the test suite: the more extensive the testsuite, the smaller the risk of breaking things in the future! We can keep code private on request.

Bug hunting/squishing

Find bugs and write more test cases! Test cases are especially very welcome, because it allows us to concentrate on fixing bugs instead of isolating them.

Going through the bugzilla database at http://gcc.gnu.org/bugzilla/ to reduce testcases posted there and add more information (for example, for which version does the testcase work, for which versions does it fail?) is also very helpful.

Proposed Extensions

Here’s a list of proposed extensions for the GNU Fortran compiler, in no particular order.

Most of these are necessary to be fully compatible with existing Fortran compilers, but they are not part of the official J3 Fortran 95 standard.

Compiler extensions:

• User-specified alignment rules for structures.

• Flag to generate Makefile info.

• Automatically extend single precision constants to double.

Contributing 169

• Compile code that conserves memory by dynamically allocating common and module storage either on stack or heap.

• Compile flag to generate code for array conformance checking (suggest -CC).

• User control of symbol names (underscores, etc).

• Compile setting for maximum size of stack frame size before spilling parts to static or heap.

• Flag to force local variables into static space.

• Flag to force local variables onto stack.

Environment Options

• Pluggable library modules for random numbers, linear algebra. LA should use BLAS calling conventions.

• Environment variables controlling actions on arithmetic exceptions like overflow, underflow, precision loss—Generate NaN, abort, default. action.

• Set precision for fp units that support it (i387).

• Variable for setting fp rounding mode.

• Variable to fill uninitialized variables with a user-defined bit pattern.

• Environment variable controlling filename that is opened for that unit number.

• Environment variable to clear/trash memory being freed.

• Environment variable to control tracing of allocations and frees.

• Environment variable to display allocated memory at normal program end.

• Environment variable for filename for * IO-unit.

• Environment variable for temporary file directory.

• Environment variable forcing standard output to be line buffered (unix).

GNU General Public License 171

GNU General Public License

Version 3, 29 June 2007

Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.

Preamble

The GNU General Public License is a free, copyleft license for software and other kinds of works.

The licenses for most software and other practical works are designed to take away your freedom to share and change the works. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change all versions of a program–to make sure it remains free software for all its users. We, the Free Software Foundation, use the

GNU General Public License for most of our software; it applies also to any other work released this way by its authors. You can apply it to your programs, too.

When we speak of free software, we are referring to freedom, not price. Our General

Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for them if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs, and that you know you can do these things.

To protect your rights, we need to prevent others from denying you these rights or asking you to surrender the rights. Therefore, you have certain responsibilities if you distribute copies of the software, or if you modify it: responsibilities to respect the freedom of others.

For example, if you distribute copies of such a program, whether gratis or for a fee, you must pass on to the recipients the same freedoms that you received. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights.

Developers that use the GNU GPL protect your rights with two steps: (1) assert copyright on the software, and (2) offer you this License giving you legal permission to copy, distribute and/or modify it.

For the developers’ and authors’ protection, the GPL clearly explains that there is no warranty for this free software. For both users’ and authors’ sake, the GPL requires that modified versions be marked as changed, so that their problems will not be attributed erroneously to authors of previous versions.

Some devices are designed to deny users access to install or run modified versions of the software inside them, although the manufacturer can do so. This is fundamentally incompatible with the aim of protecting users’ freedom to change the software. The systematic pattern of such abuse occurs in the area of products for individuals to use, which is precisely where it is most unacceptable. Therefore, we have designed this version of the GPL to prohibit the practice for those products. If such problems arise substantially in other domains, we stand ready to extend this provision to those domains in future versions of the

GPL, as needed to protect the freedom of users.

172 The GNU Fortran Compiler

Finally, every program is threatened constantly by software patents. States should not allow patents to restrict development and use of software on general-purpose computers, but in those that do, we wish to avoid the special danger that patents applied to a free program could make it effectively proprietary. To prevent this, the GPL assures that patents cannot be used to render the program non-free.

The precise terms and conditions for copying, distribution and modification follow.

TERMS AND CONDITIONS

0. Definitions.

“This License” refers to version 3 of the GNU General Public License.

“Copyright” also means copyright-like laws that apply to other kinds of works, such as semiconductor masks.

“The Program” refers to any copyrightable work licensed under this License. Each licensee is addressed as “you”. “Licensees” and “recipients” may be individuals or organizations.

To “modify” a work means to copy from or adapt all or part of the work in a fashion requiring copyright permission, other than the making of an exact copy. The resulting work is called a “modified version” of the earlier work or a work “based on” the earlier work.

A “covered work” means either the unmodified Program or a work based on the Program.

To “propagate” a work means to do anything with it that, without permission, would make you directly or secondarily liable for infringement under applicable copyright law, except executing it on a computer or modifying a private copy. Propagation includes copying, distribution (with or without modification), making available to the public, and in some countries other activities as well.

To “convey” a work means any kind of propagation that enables other parties to make or receive copies. Mere interaction with a user through a computer network, with no transfer of a copy, is not conveying.

An interactive user interface displays “Appropriate Legal Notices” to the extent that it includes a convenient and prominently visible feature that (1) displays an appropriate copyright notice, and (2) tells the user that there is no warranty for the work (except to the extent that warranties are provided), that licensees may convey the work under this License, and how to view a copy of this License. If the interface presents a list of user commands or options, such as a menu, a prominent item in the list meets this criterion.

1. Source Code.

The “source code” for a work means the preferred form of the work for making modifications to it. “Object code” means any non-source form of a work.

A “Standard Interface” means an interface that either is an official standard defined by a recognized standards body, or, in the case of interfaces specified for a particular programming language, one that is widely used among developers working in that language.

GNU General Public License 173

The “System Libraries” of an executable work include anything, other than the work as a whole, that (a) is included in the normal form of packaging a Major Component, but which is not part of that Major Component, and (b) serves only to enable use of the work with that Major Component, or to implement a Standard Interface for which an implementation is available to the public in source code form. A “Major Component”, in this context, means a major essential component (kernel, window system, and so on) of the specific operating system (if any) on which the executable work runs, or a compiler used to produce the work, or an object code interpreter used to run it.

The “Corresponding Source” for a work in object code form means all the source code needed to generate, install, and (for an executable work) run the object code and to modify the work, including scripts to control those activities. However, it does not include the work’s System Libraries, or general-purpose tools or generally available free programs which are used unmodified in performing those activities but which are not part of the work. For example, Corresponding Source includes interface definition files associated with source files for the work, and the source code for shared libraries and dynamically linked subprograms that the work is specifically designed to require, such as by intimate data communication or control flow between those subprograms and other parts of the work.

The Corresponding Source need not include anything that users can regenerate automatically from other parts of the Corresponding Source.

The Corresponding Source for a work in source code form is that same work.

2. Basic Permissions.

All rights granted under this License are granted for the term of copyright on the

Program, and are irrevocable provided the stated conditions are met. This License explicitly affirms your unlimited permission to run the unmodified Program. The output from running a covered work is covered by this License only if the output, given its content, constitutes a covered work. This License acknowledges your rights of fair use or other equivalent, as provided by copyright law.

You may make, run and propagate covered works that you do not convey, without conditions so long as your license otherwise remains in force. You may convey covered works to others for the sole purpose of having them make modifications exclusively for you, or provide you with facilities for running those works, provided that you comply with the terms of this License in conveying all material for which you do not control copyright. Those thus making or running the covered works for you must do so exclusively on your behalf, under your direction and control, on terms that prohibit them from making any copies of your copyrighted material outside their relationship with you.

Conveying under any other circumstances is permitted solely under the conditions stated below. Sublicensing is not allowed; section 10 makes it unnecessary.

3. Protecting Users’ Legal Rights From Anti-Circumvention Law.

No covered work shall be deemed part of an effective technological measure under any applicable law fulfilling obligations under article 11 of the WIPO copyright treaty adopted on 20 December 1996, or similar laws prohibiting or restricting circumvention of such measures.

174 The GNU Fortran Compiler

When you convey a covered work, you waive any legal power to forbid circumvention of technological measures to the extent such circumvention is effected by exercising rights under this License with respect to the covered work, and you disclaim any intention to limit operation or modification of the work as a means of enforcing, against the work’s users, your or third parties’ legal rights to forbid circumvention of technological measures.

4. Conveying Verbatim Copies.

You may convey verbatim copies of the Program’s source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice; keep intact all notices stating that this License and any non-permissive terms added in accord with section 7 apply to the code; keep intact all notices of the absence of any warranty; and give all recipients a copy of this License along with the Program.

You may charge any price or no price for each copy that you convey, and you may offer support or warranty protection for a fee.

5. Conveying Modified Source Versions.

You may convey a work based on the Program, or the modifications to produce it from the Program, in the form of source code under the terms of section 4, provided that you also meet all of these conditions: a. The work must carry prominent notices stating that you modified it, and giving a relevant date.

b. The work must carry prominent notices stating that it is released under this License and any conditions added under section 7. This requirement modifies the requirement in section 4 to “keep intact all notices”.

c. You must license the entire work, as a whole, under this License to anyone who comes into possession of a copy. This License will therefore apply, along with any applicable section 7 additional terms, to the whole of the work, and all its parts, regardless of how they are packaged. This License gives no permission to license the work in any other way, but it does not invalidate such permission if you have separately received it.

d. If the work has interactive user interfaces, each must display Appropriate Legal

Notices; however, if the Program has interactive interfaces that do not display

Appropriate Legal Notices, your work need not make them do so.

A compilation of a covered work with other separate and independent works, which are not by their nature extensions of the covered work, and which are not combined with it such as to form a larger program, in or on a volume of a storage or distribution medium, is called an “aggregate” if the compilation and its resulting copyright are not used to limit the access or legal rights of the compilation’s users beyond what the individual works permit. Inclusion of a covered work in an aggregate does not cause this License to apply to the other parts of the aggregate.

6. Conveying Non-Source Forms.

You may convey a covered work in object code form under the terms of sections 4 and

5, provided that you also convey the machine-readable Corresponding Source under the terms of this License, in one of these ways:

GNU General Public License 175 a. Convey the object code in, or embodied in, a physical product (including a physical distribution medium), accompanied by the Corresponding Source fixed on a durable physical medium customarily used for software interchange.

b. Convey the object code in, or embodied in, a physical product (including a physical distribution medium), accompanied by a written offer, valid for at least three years and valid for as long as you offer spare parts or customer support for that product model, to give anyone who possesses the object code either (1) a copy of the Corresponding Source for all the software in the product that is covered by this

License, on a durable physical medium customarily used for software interchange, for a price no more than your reasonable cost of physically performing this conveying of source, or (2) access to copy the Corresponding Source from a network server at no charge.

c. Convey individual copies of the object code with a copy of the written offer to provide the Corresponding Source. This alternative is allowed only occasionally and noncommercially, and only if you received the object code with such an offer, in accord with subsection 6b.

d. Convey the object code by offering access from a designated place (gratis or for a charge), and offer equivalent access to the Corresponding Source in the same way through the same place at no further charge. You need not require recipients to copy the Corresponding Source along with the object code. If the place to copy the object code is a network server, the Corresponding Source may be on a different server (operated by you or a third party) that supports equivalent copying facilities, provided you maintain clear directions next to the object code saying where to find the Corresponding Source. Regardless of what server hosts the Corresponding Source, you remain obligated to ensure that it is available for as long as needed to satisfy these requirements.

e. Convey the object code using peer-to-peer transmission, provided you inform other peers where the object code and Corresponding Source of the work are being offered to the general public at no charge under subsection 6d.

A separable portion of the object code, whose source code is excluded from the Corresponding Source as a System Library, need not be included in conveying the object code work.

A “User Product” is either (1) a “consumer product”, which means any tangible personal property which is normally used for personal, family, or household purposes, or

(2) anything designed or sold for incorporation into a dwelling. In determining whether a product is a consumer product, doubtful cases shall be resolved in favor of coverage.

For a particular product received by a particular user, “normally used” refers to a typical or common use of that class of product, regardless of the status of the particular user or of the way in which the particular user actually uses, or expects or is expected to use, the product. A product is a consumer product regardless of whether the product has substantial commercial, industrial or non-consumer uses, unless such uses represent the only significant mode of use of the product.

“Installation Information” for a User Product means any methods, procedures, authorization keys, or other information required to install and execute modified versions of a covered work in that User Product from a modified version of its Corresponding Source.

176 The GNU Fortran Compiler

The information must suffice to ensure that the continued functioning of the modified object code is in no case prevented or interfered with solely because modification has been made.

If you convey an object code work under this section in, or with, or specifically for use in, a User Product, and the conveying occurs as part of a transaction in which the right of possession and use of the User Product is transferred to the recipient in perpetuity or for a fixed term (regardless of how the transaction is characterized), the Corresponding Source conveyed under this section must be accompanied by the

Installation Information. But this requirement does not apply if neither you nor any third party retains the ability to install modified object code on the User Product (for example, the work has been installed in ROM).

The requirement to provide Installation Information does not include a requirement to continue to provide support service, warranty, or updates for a work that has been modified or installed by the recipient, or for the User Product in which it has been modified or installed. Access to a network may be denied when the modification itself materially and adversely affects the operation of the network or violates the rules and protocols for communication across the network.

Corresponding Source conveyed, and Installation Information provided, in accord with this section must be in a format that is publicly documented (and with an implementation available to the public in source code form), and must require no special password or key for unpacking, reading or copying.

7. Additional Terms.

“Additional permissions” are terms that supplement the terms of this License by making exceptions from one or more of its conditions. Additional permissions that are applicable to the entire Program shall be treated as though they were included in this

License, to the extent that they are valid under applicable law. If additional permissions apply only to part of the Program, that part may be used separately under those permissions, but the entire Program remains governed by this License without regard to the additional permissions.

When you convey a copy of a covered work, you may at your option remove any additional permissions from that copy, or from any part of it. (Additional permissions may be written to require their own removal in certain cases when you modify the work.) You may place additional permissions on material, added by you to a covered work, for which you have or can give appropriate copyright permission.

Notwithstanding any other provision of this License, for material you add to a covered work, you may (if authorized by the copyright holders of that material) supplement the terms of this License with terms: a. Disclaiming warranty or limiting liability differently from the terms of sections 15 and 16 of this License; or b. Requiring preservation of specified reasonable legal notices or author attributions in that material or in the Appropriate Legal Notices displayed by works containing it; or c. Prohibiting misrepresentation of the origin of that material, or requiring that modified versions of such material be marked in reasonable ways as different from the original version; or

GNU General Public License 177 d. Limiting the use for publicity purposes of names of licensors or authors of the material; or e. Declining to grant rights under trademark law for use of some trade names, trademarks, or service marks; or f. Requiring indemnification of licensors and authors of that material by anyone who conveys the material (or modified versions of it) with contractual assumptions of liability to the recipient, for any liability that these contractual assumptions directly impose on those licensors and authors.

All other non-permissive additional terms are considered “further restrictions” within the meaning of section 10. If the Program as you received it, or any part of it, contains a notice stating that it is governed by this License along with a term that is a further restriction, you may remove that term. If a license document contains a further restriction but permits relicensing or conveying under this License, you may add to a covered work material governed by the terms of that license document, provided that the further restriction does not survive such relicensing or conveying.

If you add terms to a covered work in accord with this section, you must place, in the relevant source files, a statement of the additional terms that apply to those files, or a notice indicating where to find the applicable terms.

Additional terms, permissive or non-permissive, may be stated in the form of a separately written license, or stated as exceptions; the above requirements apply either way.

8. Termination.

You may not propagate or modify a covered work except as expressly provided under this License. Any attempt otherwise to propagate or modify it is void, and will automatically terminate your rights under this License (including any patent licenses granted under the third paragraph of section 11).

However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.

Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice.

Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, you do not qualify to receive new licenses for the same material under section 10.

9. Acceptance Not Required for Having Copies.

You are not required to accept this License in order to receive or run a copy of the

Program. Ancillary propagation of a covered work occurring solely as a consequence of using peer-to-peer transmission to receive a copy likewise does not require acceptance.

178 The GNU Fortran Compiler

However, nothing other than this License grants you permission to propagate or modify any covered work. These actions infringe copyright if you do not accept this License.

Therefore, by modifying or propagating a covered work, you indicate your acceptance of this License to do so.

10. Automatic Licensing of Downstream Recipients.

Each time you convey a covered work, the recipient automatically receives a license from the original licensors, to run, modify and propagate that work, subject to this

License. You are not responsible for enforcing compliance by third parties with this

License.

An “entity transaction” is a transaction transferring control of an organization, or substantially all assets of one, or subdividing an organization, or merging organizations.

If propagation of a covered work results from an entity transaction, each party to that transaction who receives a copy of the work also receives whatever licenses to the work the party’s predecessor in interest had or could give under the previous paragraph, plus a right to possession of the Corresponding Source of the work from the predecessor in interest, if the predecessor has it or can get it with reasonable efforts.

You may not impose any further restrictions on the exercise of the rights granted or affirmed under this License. For example, you may not impose a license fee, royalty, or other charge for exercise of rights granted under this License, and you may not initiate litigation (including a cross-claim or counterclaim in a lawsuit) alleging that any patent claim is infringed by making, using, selling, offering for sale, or importing the Program or any portion of it.

11. Patents.

A “contributor” is a copyright holder who authorizes use under this License of the

Program or a work on which the Program is based. The work thus licensed is called the contributor’s “contributor version”.

A contributor’s “essential patent claims” are all patent claims owned or controlled by the contributor, whether already acquired or hereafter acquired, that would be infringed by some manner, permitted by this License, of making, using, or selling its contributor version, but do not include claims that would be infringed only as a consequence of further modification of the contributor version. For purposes of this definition, “control” includes the right to grant patent sublicenses in a manner consistent with the requirements of this License.

Each contributor grants you a non-exclusive, worldwide, royalty-free patent license under the contributor’s essential patent claims, to make, use, sell, offer for sale, import and otherwise run, modify and propagate the contents of its contributor version.

In the following three paragraphs, a “patent license” is any express agreement or commitment, however denominated, not to enforce a patent (such as an express permission to practice a patent or covenant not to sue for patent infringement). To “grant” such a patent license to a party means to make such an agreement or commitment not to enforce a patent against the party.

If you convey a covered work, knowingly relying on a patent license, and the Corresponding Source of the work is not available for anyone to copy, free of charge and under the terms of this License, through a publicly available network server or other readily accessible means, then you must either (1) cause the Corresponding Source to be so

GNU General Public License 179 available, or (2) arrange to deprive yourself of the benefit of the patent license for this particular work, or (3) arrange, in a manner consistent with the requirements of this

License, to extend the patent license to downstream recipients. “Knowingly relying” means you have actual knowledge that, but for the patent license, your conveying the covered work in a country, or your recipient’s use of the covered work in a country, would infringe one or more identifiable patents in that country that you have reason to believe are valid.

If, pursuant to or in connection with a single transaction or arrangement, you convey, or propagate by procuring conveyance of, a covered work, and grant a patent license to some of the parties receiving the covered work authorizing them to use, propagate, modify or convey a specific copy of the covered work, then the patent license you grant is automatically extended to all recipients of the covered work and works based on it.

A patent license is “discriminatory” if it does not include within the scope of its coverage, prohibits the exercise of, or is conditioned on the non-exercise of one or more of the rights that are specifically granted under this License. You may not convey a covered work if you are a party to an arrangement with a third party that is in the business of distributing software, under which you make payment to the third party based on the extent of your activity of conveying the work, and under which the third party grants, to any of the parties who would receive the covered work from you, a discriminatory patent license (a) in connection with copies of the covered work conveyed by you (or copies made from those copies), or (b) primarily for and in connection with specific products or compilations that contain the covered work, unless you entered into that arrangement, or that patent license was granted, prior to 28 March 2007.

Nothing in this License shall be construed as excluding or limiting any implied license or other defenses to infringement that may otherwise be available to you under applicable patent law.

12. No Surrender of Others’ Freedom.

If conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot convey a covered work so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not convey it at all. For example, if you agree to terms that obligate you to collect a royalty for further conveying from those to whom you convey the Program, the only way you could satisfy both those terms and this License would be to refrain entirely from conveying the Program.

13. Use with the GNU Affero General Public License.

Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU Affero

General Public License into a single combined work, and to convey the resulting work.

The terms of this License will continue to apply to the part which is the covered work, but the special requirements of the GNU Affero General Public License, section 13, concerning interaction through a network will apply to the combination as such.

14. Revised Versions of this License.

180 The GNU Fortran Compiler

The Free Software Foundation may publish revised and/or new versions of the GNU

General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.

Each version is given a distinguishing version number. If the Program specifies that a certain numbered version of the GNU General Public License “or any later version” applies to it, you have the option of following the terms and conditions either of that numbered version or of any later version published by the Free Software Foundation.

If the Program does not specify a version number of the GNU General Public License, you may choose any version ever published by the Free Software Foundation.

If the Program specifies that a proxy can decide which future versions of the GNU

General Public License can be used, that proxy’s public statement of acceptance of a version permanently authorizes you to choose that version for the Program.

Later license versions may give you additional or different permissions. However, no additional obligations are imposed on any author or copyright holder as a result of your choosing to follow a later version.

15. Disclaimer of Warranty.

THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PER-

MITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN

WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE

THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EX-

PRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE

OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFEC-

TIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR

CORRECTION.

16. Limitation of Liability.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN

WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO

MODIFIES AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE

LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, IN-

CIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR

INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO

LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUS-

TAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM

TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR

OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAM-

AGES.

17. Interpretation of Sections 15 and 16.

If the disclaimer of warranty and limitation of liability provided above cannot be given local legal effect according to their terms, reviewing courts shall apply local law that most closely approximates an absolute waiver of all civil liability in connection with the Program, unless a warranty or assumption of liability accompanies a copy of the

Program in return for a fee.

GNU General Public License 181

END OF TERMS AND CONDITIONS

How to Apply These Terms to Your New Programs

If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.

To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.

one line to give the program’s name and a brief idea of what it does.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

See the GNU

General Public License for more details.

You should have received a copy of the GNU General Public License along with this program.

If not, see http://www.gnu.org/licenses/ .

Also add information on how to contact you by electronic and paper mail.

If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode: program Copyright (C) year name of author

This program comes with ABSOLUTELY NO WARRANTY; for details type ‘show w’.

This is free software, and you are welcome to redistribute it under certain conditions; type ‘show c’ for details.

The hypothetical commands ‘show w’ and ‘show c’ should show the appropriate parts of the General Public License. Of course, your program’s commands might be different; for a

GUI interface, you would use an “about box”.

You should also get your employer (if you work as a programmer) or school, if any, to sign a “copyright disclaimer” for the program, if necessary. For more information on this, and how to apply and follow the GNU GPL, see http://www.gnu.org/licenses/

The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read http://www.gnu.org/philosophy/why-not-lgpl.html

GNU Free Documentation License 183

GNU Free Documentation License

Version 1.2, November 2002

51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA

Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.

0. PREAMBLE

The purpose of this License is to make a manual, textbook, or other functional and useful document free in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.

This License is a kind of “copyleft”, which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public

License, which is a copyleft license designed for free software.

We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.

1. APPLICABILITY AND DEFINITIONS

This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein.

The “Document”, below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as “you”. You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law.

A “Modified Version” of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language.

A “Secondary Section” is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document’s overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (Thus, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them.

The “Invariant Sections” are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released

184 The GNU Fortran Compiler under this License. If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document may contain zero Invariant

Sections. If the Document does not identify any Invariant Sections then there are none.

The “Cover Texts” are certain short passages of text that are listed, as Front-Cover

Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A Front-Cover Text may be at most 5 words, and a Back-Cover Text may be at most 25 words.

A “Transparent” copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, that is suitable for revising the document straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise

Transparent file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent modification by readers is not Transparent. An image format is not Transparent if used for any substantial amount of text. A copy that is not “Transparent” is called “Opaque”.

Examples of suitable formats for Transparent copies include plain ascii without markup, Texinfo input format, LaTEX input format,

SGML or

XML using a publicly available

DTD

, and standard-conforming simple

HTML

, PostScript or

PDF designed for human modification. Examples of transparent image formats include

PNG

XCF and

JPG

. Opaque formats include proprietary formats that can be read and edited only by proprietary word processors,

SGML or

XML for which the

DTD and/or processing tools are not generally available, and the machine-generated

HTML

PostScript or

PDF produced by some word processors for output purposes only.

The “Title Page” means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, “Title Page” means the text near the most prominent appearance of the work’s title, preceding the beginning of the body of the text.

A section “Entitled XYZ” means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a specific section name mentioned below, such as “Acknowledgements”, “Dedications”, “Endorsements”, or “History”.) To “Preserve the Title” of such a section when you modify the Document means that it remains a section “Entitled XYZ” according to this definition.

The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document. These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License.

2. VERBATIM COPYING

You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and

GNU Free Documentation License 185 that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies.

If you distribute a large enough number of copies you must also follow the conditions in section 3.

You may also lend copies, under the same conditions stated above, and you may publicly display copies.

3. COPYING IN QUANTITY

If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document’s license notice requires

Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition.

Copying with changes limited to the covers, as long as they preserve the title of the

Document and satisfy these conditions, can be treated as verbatim copying in other respects.

If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages.

If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using public-standard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public.

It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.

4. MODIFICATIONS

You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:

A. Use in the Title Page (and on the covers, if any) a title distinct from that of the

Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission.

186 The GNU Fortran Compiler

B. List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has fewer than five), unless they release you from this requirement.

C. State on the Title page the name of the publisher of the Modified Version, as the publisher.

D. Preserve all the copyright notices of the Document.

E. Add an appropriate copyright notice for your modifications adjacent to the other copyright notices.

F. Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below.

G. Preserve in that license notice the full lists of Invariant Sections and required Cover

Texts given in the Document’s license notice.

H. Include an unaltered copy of this License.

I. Preserve the section Entitled “History”, Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section Entitled “History” in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence.

J. Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the

“History” section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission.

K. For any section Entitled “Acknowledgements” or “Dedications”, Preserve the Title of the section, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein.

L. Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles.

M. Delete any section Entitled “Endorsements”. Such a section may not be included in the Modified Version.

N. Do not retitle any existing section to be Entitled “Endorsements” or to conflict in title with any Invariant Section.

O. Preserve any Warranty Disclaimers.

If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version’s license notice. These titles must be distinct from any other section titles.

GNU Free Documentation License 187

You may add a section Entitled “Endorsements”, provided it contains nothing but endorsements of your Modified Version by various parties—for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard.

You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified

Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one.

The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified

Version.

5. COMBINING DOCUMENTS

You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers.

The combined work need only contain one copy of this License, and multiple identical

Invariant Sections may be replaced with a single copy. If there are multiple Invariant

Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work.

In the combination, you must combine any sections Entitled “History” in the various original documents, forming one section Entitled “History”; likewise combine any sections Entitled “Acknowledgements”, and any sections Entitled “Dedications”. You must delete all sections Entitled “Endorsements.”

6. COLLECTIONS OF DOCUMENTS

You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects.

You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.

7. AGGREGATION WITH INDEPENDENT WORKS

A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, is called

188 The GNU Fortran Compiler an “aggregate” if the copyright resulting from the compilation is not used to limit the legal rights of the compilation’s users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document.

If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one half of the entire aggregate, the Document’s Cover

Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate.

8. TRANSLATION

Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4.

Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail.

If a section in the Document is Entitled “Acknowledgements”, “Dedications”, or “History”, the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title.

9. TERMINATION

You may not copy, modify, sublicense, or distribute the Document except as expressly provided for under this License. Any other attempt to copy, modify, sublicense or distribute the Document is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this

License will not have their licenses terminated so long as such parties remain in full compliance.

10. FUTURE REVISIONS OF THIS LICENSE

The Free Software Foundation may publish new, revised versions of the GNU Free

Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.

See http://www.gnu.org/copyleft/

Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License “or any later version” applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free

Software Foundation.

GNU Free Documentation License 189

ADDENDUM: How to use this License for your documents

To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2

or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover

Texts.

A copy of the license is included in the section entitled ‘‘GNU

Free Documentation License’’.

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the

“with...Texts.” line with this: with the Invariant Sections being list their titles, with the Front-Cover Texts being list, and with the Back-Cover Texts being list.

If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation.

If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU

General Public License, to permit their use in free software.

Funding Free Software 191

Funding Free Software

If you want to have more free software a few years from now, it makes sense for you to help encourage people to contribute funds for its development. The most effective approach known is to encourage commercial redistributors to donate.

Users of free software systems can boost the pace of development by encouraging for-afee distributors to donate part of their selling price to free software developers—the Free

Software Foundation, and others.

The way to convince distributors to do this is to demand it and expect it from them. So when you compare distributors, judge them partly by how much they give to free software development. Show distributors they must compete to be the one who gives the most.

To make this approach work, you must insist on numbers that you can compare, such as,

“We will donate ten dollars to the Frobnitz project for each disk sold.” Don’t be satisfied with a vague promise, such as “A portion of the profits are donated,” since it doesn’t give a basis for comparison.

Even a precise fraction “of the profits from this disk” is not very meaningful, since creative accounting and unrelated business decisions can greatly alter what fraction of the sales price counts as profit. If the price you pay is $50, ten percent of the profit is probably less than a dollar; it might be a few cents, or nothing at all.

Some redistributors do development work themselves. This is useful too; but to keep everyone honest, you need to inquire how much they do, and what kind. Some kinds of development make much more long-term difference than others. For example, maintaining a separate version of a program contributes very little; maintaining the standard version of a program for the whole community contributes much. Easy new ports contribute little, since someone else would surely do them; difficult ports such as adding a new CPU to the

GNU Compiler Collection contribute more; major new features or packages contribute the most.

By establishing the idea that supporting further development is “the proper thing to do” when distributing free software for a fee, we can assure a steady flow of resources into making more free software.

Verbatim copying and redistribution of this section is permitted without royalty; alteration is not permitted.

Option Index 193

Option Index

gfortran’s command line options are indexed here without any initial ‘-’ or ‘--’. Where an option has both positive and negative forms (such as -foption and -fno-option), relevant entries in the manual are indexed under the most appropriate form; it may sometimes be useful to look up both forms.

B

backslash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

frecursive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

frepack-arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fsecond-underscore . . . . . . . . . . . . . . . . . . . . . . . . . .

fshort-enums . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

17 ,

fsign-zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fsyntax-only . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

F

fall-intrinsics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fbacktrace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fblas-matmul-limit . . . . . . . . . . . . . . . . . . . . . . . . . .

fbounds-check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fconvert=conversion . . . . . . . . . . . . . . . . . . . . . . . . .

fcray-pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fd-lines-as-code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fd-lines-as-comments . . . . . . . . . . . . . . . . . . . . . . . . .

fdefault-double-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fdefault-integer-8 . . . . . . . . . . . . . . . . . . . . . . . . . . .

fdefault-real-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fdollar-ok . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fdump-core . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fdump-parse-tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fexternal-blas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ff2c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ffixed-line-length-n . . . . . . . . . . . . . . . . . . . . . . . . .

ffpe-trap=list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ffree-form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ffree-line-length-n . . . . . . . . . . . . . . . . . . . . . . . . . .

fimplicit-none . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

finit-character . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

finit-integer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

finit-local-zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

finit-logical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

finit-real . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fintrinsic-modules-path dir . . . . . . . . . . . . . . . .

fmax-errors=n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fmax-identifier-length=n . . . . . . . . . . . . . . . . . . . .

fmax-stack-var-size . . . . . . . . . . . . . . . . . . . . . . . . .

fmax-subrecord-length=length . . . . . . . . . . . . . . .

fmodule-private . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fno-automatic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fno-fixed-form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fno-underscoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fopenmp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

fpack-derived . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

frange-check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

frecord-marker=length . . . . . . . . . . . . . . . . . . . . . . .

I

Idir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

J

Jdir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

M

Mdir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

P

pedantic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

pedantic-errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

S

static-libgfortran . . . . . . . . . . . . . . . . . . . . . . . . . .

std=std option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

W

Waliasing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Wall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Wampersand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Wcharacter-truncation . . . . . . . . . . . . . . . . . . . . . . .

Wconversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Werror . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Wimplicit-interface . . . . . . . . . . . . . . . . . . . . . . . . .

Wnonstd-intrinsics . . . . . . . . . . . . . . . . . . . . . . . . . .

Wsurprising . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Wtabs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Wunderflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Wunused-parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Keyword Index 195

Keyword Index

[

$

$ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

%

%LOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

%REF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

%VAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

&

& . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[...] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A

ABORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

absolute value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ACCESS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ACCESS=’STREAM’ I/O . . . . . . . . . . . . . . . . . . . . . . . . .

ACHAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ACOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ACOSH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

adjust string . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ADJUSTL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ADJUSTR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

AIMAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

AINT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ALARM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ALGAMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

aliasing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ALL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

all warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ALLOCATABLE components of derived types . . . . . .

ALLOCATABLE dummy arguments . . . . . . . . . . . . . . .

ALLOCATABLE function results . . . . . . . . . . . . . . . . . .

ALLOCATED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

allocation, moving . . . . . . . . . . . . . . . . . . . . . . . . . . . .

allocation, status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ALOG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ALOG10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

AMAX0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

AMAX1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

AMIN0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

AMIN1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

AMOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

AND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ANINT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ANY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

area hyperbolic cosine . . . . . . . . . . . . . . . . . . . . . . . . .

area hyperbolic sine . . . . . . . . . . . . . . . . . . . . . . . . . . .

area hyperbolic tangent . . . . . . . . . . . . . . . . . . . . . . . .

argument list functions . . . . . . . . . . . . . . . . . . . . . . . .

arguments, to program . . . . . . . . . . . . . .

89 ,

array, add elements . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, apply condition . . . . . . . . . . . . . . . . . . . . . .

44 ,

array, bounds checking . . . . . . . . . . . . . . . . . . . . . . . . .

array, change dimensions . . . . . . . . . . . . . . . . . . . . .

array, combine arrays . . . . . . . . . . . . . . . . . . . . . . . . .

array, condition testing . . . . . . . . . . . . . . . . . . . . .

44 ,

array, conditionally add elements . . . . . . . . . . . . .

array, conditionally count elements . . . . . . . . . . . . .

array, conditionally multiply elements . . . . . . . . .

array, constructors . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, count elements . . . . . . . . . . . . . . . . . . . . . . . . .

array, duplicate dimensions . . . . . . . . . . . . . . . . . . .

array, duplicate elements . . . . . . . . . . . . . . . . . . . . .

array, element counting . . . . . . . . . . . . . . . . . . . . . . . .

array, gather elements . . . . . . . . . . . . . . . . . . . . . . . .

array, increase dimension . . . . . . . . . . . . . . . .

148 ,

array, indices of type real . . . . . . . . . . . . . . . . . . . . . .

array, location of maximum element . . . . . . . . . .

array, location of minimum element . . . . . . . . . . .

array, lower bound . . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, maximum value . . . . . . . . . . . . . . . . . . . . . . . .

array, merge arrays . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, minimum value . . . . . . . . . . . . . . . . . . . . . . . .

array, multiply elements . . . . . . . . . . . . . . . . . . . . . .

array, number of elements . . . . . . . . . . . . . . . . .

64 ,

array, packing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, permutation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, product . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, reduce dimension . . . . . . . . . . . . . . . . . . . . . . .

array, rotate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, scatter elements . . . . . . . . . . . . . . . . . . . . . . . .

array, shape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, shift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, shift circularly . . . . . . . . . . . . . . . . . . . . . . . . . .

array, size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, sum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, transmogrify . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, transpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

array, upper bound . . . . . . . . . . . . . . . . . . . . . . . . . . .

ASCII collating sequence . . . . . . . . . . . . . . . . . . .

39 ,

ASIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ASINH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

48 ,

ASSOCIATED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

association status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

association status, C pointer . . . . . . . . . . . . . . . . . . .

ATAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ATAN2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

196 The GNU Fortran Compiler

B

backslash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

backtrace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

BESJ0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

BESJ1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

BESJN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Bessel function, first kind . . . . . . . . . . . . . . . . . .

Bessel function, second kind . . . . . . . . . . . . . . . .

BESY0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

BESY1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

BESYN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

BIT_SIZE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bits, clear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bits, extract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bits, get . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bits, move . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bits, negate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bits, number of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bits, set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bits, shift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bits, shift circular . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bits, shift left . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bits, shift right . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bits, testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bits, unset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bitwise logical and . . . . . . . . . . . . . . . . . . . . . . . . .

bitwise logical exclusive or . . . . . . . . . . . . . . . .

bitwise logical not . . . . . . . . . . . . . . . . . . . . . . . . . . . .

bitwise logical or . . . . . . . . . . . . . . . . . . . . . . . . .

bounds checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

BOZ literal constants . . . . . . . . . . . . . . . . . . . . . . . . . .

BTEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

C

C_ASSOCIATED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

C_F_POINTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

C_F_PROCPOINTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

C_FUNLOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

C_LOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

calling convention . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CCOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CDABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CDCOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CDEXP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CDLOG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CDSIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CDSQRT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ceiling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CEILING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CEXP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CHAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

character set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CHDIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

checking subscripts . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CHMOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

clock ticks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CLOG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CMPLX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

code generation, conventions . . . . . . . . . . . . . . . . . . .

collating sequence,

ASCII

. . . . . . . . . . . . . . . . . . .

39 ,

command options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

command-line arguments . . . . . . . . . . .

89 ,

command-line arguments, number of . . . . . . .

62 ,

COMMAND_ARGUMENT_COUNT . . . . . . . . . . . . . . . . . . . . . .

COMPLEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

complex conjugate . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

complex numbers, conversion to . . . . . . . .

62 ,

complex numbers, imaginary part . . . . . . . . . . . . . .

complex numbers, real part . . . . . . . . . . . . . . .

72 ,

Conditional compilation . . . . . . . . . . . . . . . . . . . . . . . .

CONJG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contributing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

conversion, to character . . . . . . . . . . . . . . . . . . . . . . . .

conversion, to complex . . . . . . . . . . . . . . . . .

62 ,

conversion, to integer . . . . .

conversion, to logical . . . . . . . . . . . . . . . . . . . . . .

30 ,

conversion, to real . . . . . . . . . . . .

79 ,

135 ,

conversion, to string . . . . . . . . . . . . . . . . . . . . . . . . . . .

CONVERT specifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

core, dump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

13 ,

COS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

COSH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

cosine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

cosine, hyperbolic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

cosine, hyperbolic, inverse . . . . . . . . . . . . . . . . . . . . .

cosine, inverse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

COUNT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CPP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CPU_TIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Credits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CSHIFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CSIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CSQRT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CTIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

current date . . . . . . . . . . . . . . . . . . . . . . . . . . . .

78 ,

current time . . . . . . . . . . . . . . . . .

106 ,

154 ,

D

DABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DACOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DACOSH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DASIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DASINH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

48 ,

DATAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DATAN2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

date, current . . . . . . . . . . . . . . . . . . . . . . . . . . .

78 ,

DATE_AND_TIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DBESJ0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DBESJ1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DBESJN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DBESY0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Keyword Index 197

DBESY1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DBESYN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DBLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DCMPLX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DCONJG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DCOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DCOSH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DDIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

debugging information options . . . . . . . . . . . . . . . . .

DECODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

delayed execution . . . . . . . . . . . . . . . . . . . . . . . . .

DEXP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DFLOAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DGAMMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

dialect options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DIGITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DIMAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DINT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

directive, INCLUDE . . . . . . . . . . . . . . . . . . . . . . . . . . .

directory, options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

directory, search paths for inclusion . . . . . . . . . . . .

division, modulo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

division, remainder . . . . . . . . . . . . . . . . . . . . . . . . . . .

DLGAMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DLOG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DLOG10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DMAX1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DMIN1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DMOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DNINT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

dot product . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DOT_PRODUCT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DPROD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DREAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DSIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DSIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DSINH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DSQRT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DTAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DTANH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DTIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

E

elapsed time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ENCODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ENUM statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ENUMERATOR statement . . . . . . . . . . . . . . . . . . . . . . . . .

environment variable . . . . . . . . . . . . . . . .

18 ,

EOSHIFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

EPSILON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ERF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ERFC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

error function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

error function, complementary . . . . . . . . . . . . . . . . .

errors, limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

escape characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ETIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

EXIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

EXP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

EXPONENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

exponential function . . . . . . . . . . . . . . . . . . . . . . . . . . .

exponential function, inverse . . . . . . . . . . . . . . . . . .

expression size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

extensions, implemented . . . . . . . . . . . . . . . . . . . . . . .

extensions, not implemented . . . . . . . . . . . . . . . . . . .

F

f2c calling convention . . . . . . . . . . . . . . . . . . . . . .

14 ,

Factorial function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FDATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FDL, GNU Free Documentation License . . . . . .

183

FGET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FGETC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

file format, fixed . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8 ,

file format, free . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8 ,

file operation, file number . . . . . . . . . . . . . . . . . . . . . .

file operation, flush . . . . . . . . . . . . . . . . . . . . . . . . . . . .

file operation, position . . . . . . . . . . . . . . . . . . . . .

85 ,

file operation, read character . . . . . . . . . . . . . . .

79 ,

file operation, seek . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

file operation, write character . . . . . . . . . . . . . .

82 ,

file system, access mode . . . . . . . . . . . . . . . . . . . . . . .

file system, change access mode . . . . . . . . . . . . . . . .

file system, create link . . . . . . . . . . . . . . . . . . .

110 ,

file system, file creation mask . . . . . . . . . . . . . . . . .

file system, file status . . . . . . . . . . . . . . . .

86 ,

115 ,

file system, hard link . . . . . . . . . . . . . . . . . . . . . . . . .

file system, remove file . . . . . . . . . . . . . . . . . . . . . . . .

file system, rename file . . . . . . . . . . . . . . . . . . . . . . .

136

file system, soft link . . . . . . . . . . . . . . . . . . . . . . . . . .

FLOAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

floating point, exponent . . . . . . . . . . . . . . . . . . . . . . .

floating point, fraction . . . . . . . . . . . . . . . . . . . . . . . . .

floating point, nearest different . . . . . . . . . . . . . . .

floating point, relative spacing . . . . . . . . . . .

138 ,

floating point, scale . . . . . . . . . . . . . . . . . . . . . . . . . . .

floating point, set exponent . . . . . . . . . . . . . . . . . . .

floor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

42 ,

FLOOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FLUSH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FLUSH statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FNUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fortran 77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FPP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FPUTC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FRACTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FREE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FSEEK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FSTAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FTELL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

198 The GNU Fortran Compiler

G

g77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

g77 calling convention . . . . . . . . . . . . . . . . . . . . . .

GAMMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Gamma function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Gamma function, logarithm of . . . . . . . . . . . . . . . .

GCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GERROR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GET_COMMAND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GET_COMMAND_ARGUMENT . . . . . . . . . . . . . . . . . . . . . . . .

GET_ENVIRONMENT_VARIABLE . . . . . . . . . . . . . . . . . . .

GETARG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GETCWD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GETENV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GETGID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GETLOG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GETPID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GETUID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GMTIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GNU Compiler Collection . . . . . . . . . . . . . . . . . . . . . . .

GNU Fortran command options . . . . . . . . . . . . . . . . .

H

Hollerith constants . . . . . . . . . . . . . . . . . . . . . . . . . . . .

HOSTNM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

HUGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

hyperbolic arccosine . . . . . . . . . . . . . . . . . . . . . . . . . . .

hyperbolic arcsine . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

hyperbolic arctangent . . . . . . . . . . . . . . . . . . . . . . . . . .

hyperbolic cosine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

hyperbolic function, cosine . . . . . . . . . . . . . . . . . . . . .

hyperbolic function, cosine, inverse . . . . . . . . . . . . .

hyperbolic function, sine . . . . . . . . . . . . . . . . . . . . . .

hyperbolic function, sine, inverse . . . . . . . . . . . . . . .

hyperbolic function, tangent . . . . . . . . . . . . . . . . . .

hyperbolic function, tangent, inverse . . . . . . . . . . .

hyperbolic sine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

hyperbolic tangent . . . . . . . . . . . . . . . . . . . . . . . . . . .

IFIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IMAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IMAGPART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IMPORT statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

INCLUDE directive . . . . . . . . . . . . . . . . . . . . . . . . . . .

inclusion, directory search paths for . . . . . . . . . . . .

INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

INT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

INT2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

INT8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

integer kind . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

intrinsic Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

intrinsic procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IOMSG= specifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IOSTAT, end of file . . . . . . . . . . . . . . . . . . . . . . . . . .

IOSTAT, end of record . . . . . . . . . . . . . . . . . . . . . . .

IRAND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IS_IOSTAT_END . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IS_IOSTAT_EOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISATTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISHFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISHFTC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISNAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISO C Bindings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISO_FORTRAN_ENV statement . . . . . . . . . . . . . . . . . . .

ITIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

K

KILL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

kind . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

KIND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

kind, integer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

kind, old-style . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

kind, real . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I

I/O item lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IACHAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IAND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IARGC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IBCLR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IBITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IBSET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ICHAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IDATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IDIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IDINT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IDNINT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IEEE, ISNAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IEOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IERRNO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

L

language, dialect options . . . . . . . . . . . . . . . . . . . . . . . .

LBOUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

LEN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

LEN_TRIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

lexical comparison of strings . . . . . . . .

109 ,

110 ,

LGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

109

LGT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

libf2c calling convention . . . . . . . . . . . . . . . . . . . .

14 ,

limits, largest number . . . . . . . . . . . . . . . . . . . . . . . . .

limits, smallest number . . . . . . . . . . . . . . . . . . . . . . .

LINK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

linking, static . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

LLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

LLT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

LNBLNK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

LOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

location of a variable in memory . . . . . . . . . . . . . .

LOG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Keyword Index 199

LOG10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

logarithmic function . . . . . . . . . . . . . . . . . . . . . . . . . .

logarithmic function, inverse . . . . . . . . . . . . . . . . . . .

LOGICAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

logical and, bitwise . . . . . . . . . . . . . . . . . . . . . . . . .

logical exclusive or, bitwise . . . . . . . . . . . . . . . .

logical not, bitwise . . . . . . . . . . . . . . . . . . . . . . . . . . .

logical or, bitwise . . . . . . . . . . . . . . . . . . . . . . . .

LONG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

LSHIFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

LSTAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

LTIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

M

MALLOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MATMUL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

matrix multiplication . . . . . . . . . . . . . . . . . . . . . . . . .

matrix, transpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MAX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MAX0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MAX1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MAXEXPONENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

maximum value . . . . . . . . . . . . . . . . . . . . . . . . . .

MAXLOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MAXVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MCLOCK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MCLOCK8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MERGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

messages, error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

messages, warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MIN0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MIN1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MINEXPONENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

minimum value . . . . . . . . . . . . . . . . . . . . . . . . . .

MINLOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MINVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

model representation, base . . . . . . . . . . . . . . . . . . . .

model representation, epsilon . . . . . . . . . . . . . . . . . .

model representation, largest number . . . . . . . . . .

model representation, maximum exponent . . . .

model representation, minimum exponent . . . . .

model representation, precision . . . . . . . . . . . . . . .

model representation, radix . . . . . . . . . . . . . . . . . . .

model representation, range . . . . . . . . . . . . . . . . . . .

model representation, significant digits . . . . . . . . .

model representation, smallest number . . . . . . . .

module entities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

module search path . . . . . . . . . . . . . . . . . . . . . . . . . . . .

modulo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MODULO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MOVE_ALLOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

moving allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . .

multiply array elements . . . . . . . . . . . . . . . . . . . . . . .

MVBITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

N

Namelist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

NEAREST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

NEW_LINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

newline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

NINT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

NOT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

NULL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

O

OpenMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9 ,

operators, unary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

options, code generation . . . . . . . . . . . . . . . . . . . . . . .

options, debugging . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

options, dialect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

options, directory search . . . . . . . . . . . . . . . . . . . . . . .

options, errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

options, fortran dialect . . . . . . . . . . . . . . . . . . . . . . . . . .

options, gfortran command . . . . . . . . . . . . . . . . . . . .

options, linking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

options, negative forms . . . . . . . . . . . . . . . . . . . . . . . . .

options, run-time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

options, runtime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

options, warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

OR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

output, newline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

P

PACK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

paths, search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

PERROR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

pointer, C address of pointers . . . . . . . . . . . . . . . . . .

pointer, C address of procedures . . . . . . . . . . . . . . .

pointer, C association status . . . . . . . . . . . . . . . . . . .

pointer, convert C to Fortran . . . . . . . . . . . . . . . . . .

pointer, cray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

84 ,

pointer, Cray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

pointer, disassociated . . . . . . . . . . . . . . . . . . . . . . . . .

pointer, status . . . . . . . . . . . . . . . . . . . . . . . . . . . .

48 ,

positive difference . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

PRECISION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Preprocessing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

PRESENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

private . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

procedure pointer, convert C to Fortran . . . . . . . .

process id . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

PRODUCT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

product, double-precision . . . . . . . . . . . . . . . . . . . . . .

product, matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

product, vector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

program termination . . . . . . . . . . . . . . . . . . . . . . . . . . .

program termination, with core dump . . . . . . . . . .

PROTECTED statement . . . . . . . . . . . . . . . . . . . . . . . . . .

200 The GNU Fortran Compiler

R

RADIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

RAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

RAND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

random number generation . . . . . . . . . . . . . .

random number generation, seeding . . . . . .

RANDOM_NUMBER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

RANDOM_SEED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

RANGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

range checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

read character, stream mode . . . . . . . . . . . . . . .

REAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

real kind . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

real number, exponent . . . . . . . . . . . . . . . . . . . . . . . . .

real number, fraction . . . . . . . . . . . . . . . . . . . . . . . . . .

real number, nearest different . . . . . . . . . . . . . . . . .

real number, relative spacing . . . . . . . . . . . . .

real number, scale . . . . . . . . . . . . . . . . . . . . . . . . . . . .

real number, set exponent . . . . . . . . . . . . . . . . . . . .

REALPART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

RECORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

remainder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

RENAME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

136

repacking arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

REPEAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

RESHAPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

root . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

rounding, ceiling . . . . . . . . . . . . . . . . . . . . . . . . . . .

rounding, floor . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

rounding, nearest whole number . . . . . . . . . . . . . .

RRSPACING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

RSHIFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

S

SAVE statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SCALE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SCAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

139

search path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

search paths, for included files . . . . . . . . . . . . . . . . .

SECNDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECOND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

seeding a random number generator . . . . . .

SELECTED_INT_KIND . . . . . . . . . . . . . . . . . . . . . . . . . .

SELECTED_REAL_KIND . . . . . . . . . . . . . . . . . . . . . . . . .

SET_EXPONENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SHAPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SHORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

sign copying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SIGNAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

sine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

sine, hyperbolic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

sine, hyperbolic, inverse . . . . . . . . . . . . . . . . . . . . . . . .

sine, inverse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SINH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SIZE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

size of a variable, in bits . . . . . . . . . . . . . . . . . . . . . . .

size of an expression . . . . . . . . . . . . . . . . . . . . . . . . . .

SIZEOF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SLEEP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SNGL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SPACING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SPREAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SQRT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

square-root . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SRAND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

STAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

statement, ENUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

statement, ENUMERATOR . . . . . . . . . . . . . . . . . . . . . . . .

statement, FLUSH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

statement, IMPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

statement, ISO_FORTRAN_ENV . . . . . . . . . . . . . . . . . . .

statement, PROTECTED . . . . . . . . . . . . . . . . . . . . . . . . . .

statement, SAVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

statement, USE, INTRINSIC . . . . . . . . . . . . . . . . . . . .

statement, VALUE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

statement, VOLATILE . . . . . . . . . . . . . . . . . . . . . . . . . . .

STREAM I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

stream mode, read character . . . . . . . . . . . . . . .

79 ,

stream mode, write character. . . . . . . . . . . . . . .

82 ,

string, adjust left . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

string, adjust right. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

string, comparison . . . . . . . . . . . . . . . . . .

109 ,

110 ,

string, concatenate . . . . . . . . . . . . . . . . . . . . . . . . . . .

string, find missing set . . . . . . . . . . . . . . . . . . . . . . . .

string, find non-blank character . . . . . . . . . . . . . . .

string, find subset . . . . . . . . . . . . . . . . . . . . . . . . . . . .

139

string, find substring . . . . . . . . . . . . . . . . . . . . . . . . .

string, length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

string, length, without trailing whitespace. . . . .

string, remove trailing whitespace . . . . . . . . . . . . .

string, repeat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

STRUCTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

structure packing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

subscript checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

substring position . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

sum array elements . . . . . . . . . . . . . . . . . . . . . . . . . . .

suppressing warnings . . . . . . . . . . . . . . . . . . . . . . . . . .

symbol names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

symbol names, transforming . . . . . . . . . . . . . . . .

15 ,

symbol names, underscores . . . . . . . . . . . . . . . . .

15 ,

SYMLNK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

syntax checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

system, error handling . . . . . . . . . . . . . . . . .

87 ,

99 ,

system, group id . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

system, host name . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

system, login name . . . . . . . . . . . . . . . . . . . . . . . . . . . .

system, process id . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

system, signal handling . . . . . . . . . . . . . . . . . . . . . . .

system, system call . . . . . . . . . . . . . . . . . . . . . . . . . . .

system, terminal . . . . . . . . . . . . . . . . . . . . . . . . .

104 ,

Keyword Index 201 system, user id . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

system, working directory . . . . . . . . . . . . . . . . . .

SYSTEM_CLOCK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

T

tabulators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

tangent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

tangent, hyperbolic . . . . . . . . . . . . . . . . . . . . . . . . . . .

tangent, hyperbolic, inverse . . . . . . . . . . . . . . . . . . . .

tangent, inverse . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TANH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

terminate program . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

terminate program, with core dump . . . . . . . . . . . .

TIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

154

time, clock ticks . . . . . . . . . . . . . . . . . . . . . . . . .

time, conversion to GMT info . . . . . . . . . . . . . . . . . .

time, conversion to local time info . . . . . . . . . . . .

time, conversion to string . . . . . . . . . . . . . . . . . . . . . .

time, current . . . . . . . . . . . . . . . .

time, elapsed . . . . . . . . . . . . . . . . . . . . . .

65 ,

TIME8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TINY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TR 15581 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

trace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TRANSFER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

transforming symbol names . . . . . . . . . . . . . . . .

transpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TRANSPOSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

trigonometric function, cosine . . . . . . . . . . . . . . . . . .

trigonometric function, cosine, inverse . . . . . . . . . .

trigonometric function, sine . . . . . . . . . . . . . . . . . . .

trigonometric function, sine, inverse . . . . . . . . . . . .

trigonometric function, tangent . . . . . . . . . . . . . . .

trigonometric function, tangent, inverse . . . .

TRIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TTYNAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

type cast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

U

UBOUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

UMASK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

underflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

underscore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

15 ,

UNLINK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

UNPACK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

unused parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

USE, INTRINSIC statement . . . . . . . . . . . . . . . . . . . . .

user id . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

V

VALUE statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

vector product . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

VERIFY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

VOLATILE statement . . . . . . . . . . . . . . . . . . . . . . . . . . .

W

warnings, aliasing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

warnings, all . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

warnings, ampersand . . . . . . . . . . . . . . . . . . . . . . . . . .

warnings, character truncation . . . . . . . . . . . . . . . . .

warnings, conversion . . . . . . . . . . . . . . . . . . . . . . . . . . .

warnings, implicit interface . . . . . . . . . . . . . . . . . . . .

warnings, non-standard intrinsics . . . . . . . . . . . . . .

warnings, suppressing . . . . . . . . . . . . . . . . . . . . . . . . . .

warnings, suspicious code . . . . . . . . . . . . . . . . . . . . . .

warnings, tabs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

warnings, to errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

warnings, underflow . . . . . . . . . . . . . . . . . . . . . . . . . . .

warnings, unused parameter . . . . . . . . . . . . . . . . . . .

write character, stream mode. . . . . . . . . . . . . . .

82 ,

X

XOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Z

ZABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ZCOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ZEXP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ZLOG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ZSIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ZSQRT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .