## fit_feng - tpcclib 0.7.8 © 2022 by Turku PET Centre

Non-linear fitting of the exponential based function suggested by
Feng et al (1993) to the PET plasma or blood time-activity curve (TAC).
Function:
when t<=dt : f(t) = 0
when t>dt : f(t) = (p1*(t-dt)-p3-p5)*exp(p2*(t-dt))
+ p3*exp(p4*(t-dt)) + p5*exp(p6*(t-dt))
Usage: fit_feng [Options] tacfile [parfile]
Options:
-lim[=<filename>]
Specify the constraints for function parameters;
This file with default values can be created by giving this
option as the only command-line argument to this program.
Without file name the default values are printed on screen.
-integ[ral]
Given datafile contains the AUC of TAC as function of time.
-wf
Weight by sampling interval.
-n=<2|3|4|A>
The nr of exponential functions; A=determined automatically.
Default is 3; changing the default may lead to a bad fit.
-ss
Function approaches steady level; last exponent term is a constant,
i.e. either p6 or p8 is 0.
-delay=<time>
Delay time (dt) is constrained to specified value (>=0).
-MRL
Error is returned if MRL check is not passed.
-fast or -safe
Speed up the fitting but increase the chance of failure, or
increase the reliability at the cost of computing time
-res=<Filename>
Fitted parameters are also written in result file format.
-svg=<Filename>
Fitted and measured TACs are plotted in specified SVG file.
-svg1=<Filename>
Initial part of fitted and measured TACs are plotted in SVG file
-svg2=<Filename>
Lower part of fitted and measured TACs are plotted in SVG file
-fit=<Filename>
Fitted TACs are written in TAC format.
-h, --help
Display usage information on standard output and exit.
-v, --version
Display version and compile information on standard output and exit.
-d[n], --debug[=n], --verbose[=n]
Set the level (n) of debugging messages and listings.
-q, --quiet
Suppress displaying normal results on standard output.
-s, --silent
Suppress displaying anything except errors.
TAC file must contain at least two columns, sample times in the first,
and concentrations of TACs in the following columns.
To obtain a good fit, TAC should be corrected for physical decay and any
circulating metabolites.
Function parameters (p1, ..., dt) will be written in the parfile.
References:
1. Feng D, Huang S-C, Wang X. Models for computer simulation studies of input
functions for tracer kinetic modeling with positron emission tomography.
Int J Biomed Comput. 1993;32:95-110.
See also: fit2dat, fit_sinf, fit_exp, fit_dexp, fit_ratf, extrapol
Keywords: curve fitting, input, modelling, simulation