fit_sigm - tpcclib 0.7.3 © 2019 by Turku PET Centre

Non-linear fitting of the Hill function (sigmoid function) to a (xi,yi)
curve data. Optionally, a background term B is added to the function:
 
       f(x) = (A * x^n ) / ( x^n + K ) + B , where A>=0, K>0, n>0, B>=0 
 
Function for estimating EC50 from sigmoidal dose-response curve is obtained
by rearranging and marking n=HillSlope, A=Top-Bottom, B=Bottom, and
K=EC50^n :
 
       f(x) = Bottom + (Top-Bottom)/(1 + (EC50/x)^HillSlope)
 
With HillSlope constrained to 1 (see options below) the function reduces to
unconstrained one site binding hyperbola, f(x)=Top*x/(EC50+x).
 
Usage: fit_sigm [Options] tacfile [fitfile]
 
Options:
 -EC50
     EC50 is estimated by fitting sigmoidal dose-response curve function
     when drug concentrations are on a linear scale (not on a log scale);
     By default, parameter Top is fitted and Bottom is constrained to 0,
     which can be changed with options (see below).
 -w1 All weights are set to 1.0 (no weighting); by default, weights in
     data file are used, if available.
 -wf
     Weight by sampling interval.
 -n=<value>
     Parameter n or HillSlope is constrained to the given value; set -n=1
     to fit one site binding hyperbola.
 -B  Parameter B or Bottom is fitted; by default B=0
 -B=<value>
     Parameter B or Bottom is constrained to the given value.
 -A=<value>
     Parameter Top is constrained to the given value; currently this option
     does not affect parameter A in the default function.
 -MRL
     Error is returned if MRL check is not passed.
 -res=<Filename>
     Fitted parameters are also written in result file format (3).
 -svg=<Filename>
     Fitted and measured TACs are plotted in specified SVG file.
 -fit=<Filename>
     Fitted TACs are written in DFT 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 2 columns, sample times (or concentrations)
and measurement values (or receptor occupancies).
Weights can be specified as usual if data is in DFT format (1).
 
Program writes the fit start and end times, nr of points, WSS,
and parameters of the fitted function to the fit file (2).
 
References:
1. http://www.turkupetcentre.net/analysis/doc/format_dft.html
2. http://www.turkupetcentre.net/analysis/doc/format_fit.html
3. http://www.turkupetcentre.net/analysis/doc/format_res.html
 
See also: fit_hiad, fit_ppf, fit_exp, fit_ratf, fit_bpr, fit2dat, tacinv
 
Keywords: curve fitting, Hill function, sigmoid, EC50, dose-response curve