/usr/share/psychtoolbox-3/Psychometric/WeibYNFitFun.m is in psychtoolbox-3-common 3.0.9+svn2579.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 | function [f,g] = WeibFitFun(x,level,nYes,nNo)
% [f,g] = WeibYNFitFun(x,level,nYes,nNo)
%
alpha = x(1);
beta = x(2);
% nData = nYes + nNo;
pYes = ComputeWeibYN(level,alpha,beta);
% Handle range problem, can't take log(0);
tol = 1e-4;
z_index = find(pYes == 0);
if (~isempty(z_index))
pYes(z_index) = tol*ones(length(z_index),1);
end
o_index = find(pYes == 1);
if (~isempty(o_index))
pYes(o_index) = (1-tol)*ones(length(o_index),1);
end
% Compute error
tmp = nYes.*log(pYes) + nNo.*log(1 - pYes);
f = -sum(tmp);
g = -1;
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