/usr/share/octave/site/m/vlfeat/toolbox/special/vl_dsigmoid.m is in octave-vlfeat 0.9.17+dfsg0-6+b1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | function y = vl_dsigmoid(x)
% VL_DSIGMOID Derivative of the sigmoid function
% Y = VL_DSIGMOID(X) returns the derivative of VL_SIGMOID(X). This is
% calculated as - VL_SIGMOID(X) * (1 - VL_SIGMOID(X)).
%
% See also: VL_SIGMOID(X), VL_HELP().
% Copyright (C) 2007-12 Andrea Vedaldi and Brian Fulkerson.
% All rights reserved.
%
% This file is part of the VLFeat library and is made available under
% the terms of the BSD license (see the COPYING file).
t = vl_sigmoid(x) ;
y = t .* (1 - t) ;
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