function f = make_gaussian_filter(sigma, cutoff)
%MAKE_GAUSSIAN_FILTER   Create Gaussian filter
%   MAKE_GAUSSSIAN_FILTER(SIGMA[, CUTOFF]) creates a Gaussian filter with
%   standard deviation SIGMA.  The filter mask is cut off at CUTOFF times
%   the standard deviation.  If CUTOFF is omitted, a default value of 3
%   is assumed.
%
%   See also FSPECIAL.
%  
%   Author:  Stefan Roth, Department of Computer Science, TU Darmstadt
%   Contact: sroth@cs.tu-darmstadt.de
%   $Date$
%   $Revision$

% Copyright 2004-2007, Brown University, Providence, RI. USA
% Copyright 2007-2010 TU Darmstadt, Darmstadt, Germany.
% 
%                          All Rights Reserved
% 
% All commercial use of this software, whether direct or indirect, is
% strictly prohibited including, without limitation, incorporation into in
% a commercial product, use in a commercial service, or production of other
% artifacts for commercial purposes.     
%
% Permission to use, copy, modify, and distribute this software and its
% documentation for research purposes is hereby granted without fee,
% provided that the above copyright notice appears in all copies and that
% both that copyright notice and this permission notice appear in
% supporting documentation, and that the name of the author and Brown
% University not be used in advertising or publicity pertaining to
% distribution of the software without specific, written prior permission.        
%
% For commercial uses contact the Technology Venture Office of Brown University
% 
% THE AUTHOR AND BROWN UNIVERSITY DISCLAIM ALL WARRANTIES WITH REGARD TO
% THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
% FITNESS FOR ANY PARTICULAR PURPOSE.  IN NO EVENT SHALL THE AUTHOR OR
% BROWN UNIVERSITY BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
% DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
% PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
% ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
% THIS SOFTWARE.        
  
  if (nargin < 2)
    cutoff = 3;
  end
  
  sz = ceil(cutoff * sigma);
  
  f = exp(-(-sz:sz).^2 / (2*sigma^2));
  f = f ./ sum(f);