DecayFit23 Class Reference

#include <DecayFit23.h>

Static Public Member Functions
static int	modelf (double *param, double *irf, double *bg, int Nchannels, double dt, double *corrections, double *mfunction)
	Single exponential model function with single rotational correlation time, with scatter contribution (BIFL scatter model)
static double	targetf (double *x, void *pv)
	Target function (to minimize) for fit23.
static double	fit (double *x, short *fixed, MParam *p)
static void	correct_input (double *x, double *xm, LVDoubleArray *corrections, int return_r)

Member Function Documentation

correct_input()

static void DecayFit23::correct_input ( double * x, double * xm, LVDoubleArray * corrections, int return_r )

static

Correct input parameters and compute anisotropy

This function corrects the input parameters for fit23 and takes care of unreasonable values. The fluorescence lifetime is constraint to positive values, gamma (the fraction of scattered light) is constraint to values between 0.0 and 0.999, the rotational correlation time rho is (if the global variable fixedrho is set to true) to the value that corresponds to the Perrin equation (for the computed, experimental anisotropy). Moreover, this function computes the anisotropy based on the corrected (g-factor, l1, l2, background) intensities, if the variable return_r is set to true.

Parameters

x[in,out]	array of length 8 that contains parameters x[0] fluorescence lifetime - tau; x[1] fraction of scattered light - gamma; x[2] fundamental anisotropy - r0 x[3] rotational time - rho; x[4] softbifl - flag specifying the type of bifl fit (not used here) x[5] p2s_twoIstar - flag specifying the type of chi2 calculation (not used here) x[6] background corrected anisotropy x[7] anisotropy without background correction
xm[in,out]	array that will contain the corrected parameters
corrections[in]
return_r[in]	if set to true (positive) computes the anisotropy and returns the scatter corrected and the signal (no scatter correction) anisotropy and writes the values to the input/output vector x.

fit()

static double DecayFit23::fit ( double * x, short * fixed, MParam * p )

static

Function that optimizes parameters of model23 to data.

Parameters

x[in,out]	a vector of length that that contains the starting parameters for the optimization and is used to return the optimized parameters. [0] fluorescence lifetime - tau (in,out) [1] fraction of scattered light - gamma (in,out) [2] fundamental anisotropy - r0 () [3] rotational correlation time - rho (in,out) [4] if negative reduce contribution of background photons from scoring function - Soft BIFL scatter fit? (flag) (in) [5] specifies type of score that is returned - 2I*: P+2S? (flag), this parameter only affects the returned score and does not influence the fitting (in) [6] background corrected anisotropy - r Scatter (out) [7] anisotropy without background correction - r Experimental (out)
fixed	an array at least of length 4 for the parameters tau, gamma, r0, and rho that specifies if a parameter is optimized. If a value is set to 1, the parameter is optimized.
p	an instance of MParam that contains all relevant information, i.e., experimental data, the instrument response function, the needed corrections ( g-factor, l1, l2)

Returns

modelf()

static int DecayFit23::modelf ( double * param, double * irf, double * bg, int Nchannels, double dt, double * corrections, double * mfunction )

static

Single exponential model function with single rotational correlation time, with scatter contribution (BIFL scatter model)

This function computes the fluorescence decay in the parallel and perpendicular detection channel for a single exponential decay with a fluorescence lifetime tau, a single rotational correlation time rho, and separate instrument response functions for the parallel and perpendicular detection channels. The model considers the faction of scattered light in the two detection channels by the parameter gamma. The scattered light contribution is handled by patterns for the light in the parallel and perpendicular detection channel.

The instrument response function, the background, and the computed model function are in the Jordi format, i.e., stacked one-dimensional arrays of the parallel and perpendicular detection channel.

Parameters

[in]	param	array containing the model parameters [0] tau, [1] gamma, [2] r0, [3] rho
[in]	irf	instrument response function in Jordi format (parallel, perpendicular)
	bg[in]	background pattern in Jordi format (parallel, perpendicular)
	Nchannels[in]	number of channels (half the length of the Jordi arrays)
	dt[in]	time difference between two consecutive counting channels
	corrections[in]	[0] excitation period, [1] g factor, [2] l1, [3] l2, [4] convolution stop channel number
	mfunction[out]	output array of the computed decay in Jordi format. The output array has to have twice the number of channels. It needs to be allocated by beforehand.

Returns

integer (not used, 0 by default)

targetf()

static double DecayFit23::targetf ( double * x, void * pv )

static

Target function (to minimize) for fit23.

Computes the model function 23 and returns a score that quantifies the discrepancy between the data and the model.

Parameters

x[in,out]

a vector of length that that contains the starting parameters for the optimization and is used to return the optimized parameters. [0] fluorescence lifetime - tau (in) [1] fraction of scattered light - gamma (in) [2] fundamental anisotropy - r0 (in) [3] rotational correlation time - rho (in) [4] if negative reduce contribution of background photons from scoring function - Soft BIFL scatter fit? (flag) (in) [5] specifies type of score that is returned - 2I*: P+2S? (flag), this parameter only affects the returned score and does not influence the fitting (in) [6] background corrected anisotropy - r Scatter (out) [7] anisotropy without background correction - r Experimental (out)

pv[in]

a pointer to a MParam structure that contains the data and a set of corrections.

Returns

a normalized chi2

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The documentation for this class was generated from the following file:

• /builds/skf/tttrlib/include/DecayFit23.h