%SIGM Sigmoid map% %   W = W*SIGM%   B = A*SIGM%   W = W*SIGM([],SCALE)%   B = SIGM(A,SCALE)% % INPUT%   A        Dataset (optional)%   SCALE    Scaling parameter (optional, default: 1)% % OUTPUT%   W        Sigmoid mapping, or%   B        Dataset A mapped by sigmoid mapping%% DESCRIPTION% Sigmoidal transformation, useful to transform a map to classifier,% producing posterior probability estimates. The parameter SCALE scales the% data first (A/SCALE), before the transformation. Default: SCALE = 1, i.e.% no scaling.%% SEE ALSO% DATASETS, MAPPINGS, CLASSC% Copyright: R.P.W. Duin, duin@ph.tn.tudelft.nl% Faculty of Applied Sciences, Delft University of Technology% P.O. Box 5046, 2600 GA Delft, The Netherlands% $Id: sigm.m,v 1.3 2003/08/18 14:06:20 pavel Exp $function out = sigm (a,scale)	prtrace(mfilename);	if (nargin < 2)		prwarning(3,'no scale supplied, assuming 1');		scale = []; 	end	% Depending on the type of call, return a mapping or sigmoid-mapped data.	if (nargin == 0) | (isempty(a))		w = mapping(mfilename,'fixed',scale);		w = setname(w,'Sigmoidal Mapping');		out = w;	elseif (isempty(scale))		out = 1./(1+exp(-a));	else		out = 1./(1+exp(-a/scale));	end	return