/usr/share/octave/site/m/vlfeat/toolbox/special/vl_dgaussian.m is in octave-vlfeat 0.9.17+dfsg0-6build1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | function y = vl_dgaussian(x)
% VL_DGAUSSIAN Derivative of the Gaussian density function
% Y=VL_DGAUSSIAN(X) evaluates the derivative of the standard Gaussian
% density.
%
% To obtain the Gaussian density of standard deviation S, do
%
% Y = 1/S^2 * VL_DGAUSSIAN(X/S) .
%
% See also: VL_GAUSSIAN(), VL_DDGAUSSIAN(), 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).
y = -x/sqrt(2*pi) .* exp(-0.5*x.^2) ;
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