pCLAMP 10 User Guide

Exponential, Standard

The fit solves for the amplitude

A

, the time constant

τ

for each component

i

, and the common parameters, the slope

m

and constant

y

-offset

C

for each component

i

.

The recommended fitting method is Chebyshev.

EXPONENTIAL, STANDARD

=

n

∑

i

= 1

A i e

–

t

⁄ τ

i

+

C

This is the most basic function used to fit changes in current or voltage that are controlled by one or more first-order processes. The fit solves for the amplitude

A

, the time constant

τ

, and the constant

y

-offset

C

for each component

i

.

The recommended fitting method is Chebyshev.

EXPONENTIAL, WEIGHTED

f t

=

K

0

⎜

⎝

⎛

n

∑

i

=

1

f i e

–

K i t

⎟

⎠

⎞

+

C

This function is identical to the constrained exponential function except that the sum of the

f i

components is not constrained to 1.

The fit solves for the proportion (amplitude)

f

, the rate constant

K

, the “weight”

K0

and the constant

y

-offset

C

for each component

i

.

The recommended fitting method is Levenberg-Marquardt.

EXPONENTIAL, WEIGHTED/CONSTRAINED

f t

=

K

0

⎜

⎝

⎛

n

∑

i

= 1

f i e

–

K i t

⎟

⎠

⎞

+

C

where

>

Requires the variable metric fitting method.

n

∑

f i

=

1.0

i

= 1

This function has been used to describe the recovery rate of ground-state absorption following photo-excitation of intercalated metal complexes bound to DNA (Arkin, et

al. 1996).

The fit solves for the proportion (amplitude)

f

, the rate constant K, the weight

K0

and the constant

y

-offset

C

for each component

i

. The

f i

terms sum to 1.0.

The fitting method must be variable metric.

pCLAMP 10 User Guide — 1-2500-0180 Rev. A

217