function sk = skewness(xn,xnmean,xn1sig)
%
%  Name: skewness
%
%  Usage: sk = skewness(xn,xnmean,xn1sig)
%
%  Computes skewness (3rd moment) of distribution
%  (approaches zero for normal distribution)
%

%
%  Version SWD970422
%

if exist('xnmean') ~=1, xnmean = mean(xn); end
if exist('xn1sig') ~=1, xn1sig = std(xn); end

sk = mean(((xn - xnmean)/xn1sig).^3);


return
