/usr/share/psychtoolbox-3/Psychometric/FitWeibTAFC.m is in psychtoolbox-3-common 3.0.11.20140816.dfsg1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 | function [alpha,beta,thresh92] = FitWeibTAFC(inputs,nCorrect,nError,...
alpha0,beta0)
% [alpha,beta,thresh92] = FitWeibTAFC(inputs,nCorrect,nError,...
% [alpha0],[beta0])
%
% Maximum likelihood fit of a Weibull function to TAFC psychometric data.
%
% Requires the optimization toolbox. Doesn't work with Octave yet.
%
% INPUTS:
% inputs: Contains the input levels
% nCorrect: Contains the number of yes responses at
% the corresponding input level
% nError: Contains the number of no responses at
% the corresponding input level
% alpha0: Initial guess for alpha (optional)
% beta0: Initial guess for beta (optional)
% OUTPUTS:
% alpha Weibull alpha parameter
% beta Weibull beta parameter
% thresh92 92% percent correct threshold
%
% See also: FitWeibAlphTAFC, FitWeibYN, FitCumNormYN, FitLogitYN
%
% 8/25/94 dhb, ccc Cleaned comments, return 92% correct threshold
% 2/5/97 dhb Check if fminu is not available.
% Add slope test.
% 4/26/97 dhb Fix bug in threshold assignment
% 10/13/00 dhb Improve initial guess for alpha. Thanks to Duje Tadin
% for identifying the need for this.
% 4/18/02 dhb Suppress warnings in calls to optimization toolbox.
% 3/5/05 dhb Update for optimization toolbox version 2.
% Determine whether function is increasing or decreasing
lineParams = [inputs ones(size(inputs))]\(nCorrect ./ (nCorrect+nError) );
slope = lineParams(1);
% Initial parameters
if (nargin <= 3 || isempty(alpha0))
x0(1) = mean(inputs);
else
x0(1) = alpha0;
end
if (nargin <= 4)
if (slope > 0)
x0(2) = 3.5;
else
x0(2) = -3.5;
end
elseif (isempty(beta0) )
x0(2) = 3.5;
else
x0(2) = beta0;
end
% Check for needed optimization toolbox, and version.
if (exist('fminunc') == 2)
options = optimset;
options = optimset(options,'Diagnostics','off','Display','off');
options = optimset(options,'LargeScale','off');
x1 = fminunc('WeibTAFCFitFun',x0,options,inputs,nCorrect,nError);
x = fminunc('WeibTAFCFitFun',x1,options,inputs,nCorrect,nError);
elseif (exist('fminu') == 2)
options = foptions;
state = warning; warning('off');
x1 = fminu('WeibTAFCFitFun',x0,options,[],inputs,nCorrect,nError);
x = fminu('WeibTAFCFitFun',x1,options,[],inputs,nCorrect,nError);
warning(state);
else
error('FitWeibTAFC requires the optional Matlab Optimization Toolbox from Mathworks');
end
% Extract parameters
alpha = x(1);
beta = x(2);
% Compute threshold from fit parameters
thresh92 = FindThreshWeibTAFC(0.92,alpha,beta);
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