% K = KURT2(MTX,MEAN,VAR)%% Sample kurtosis (fourth moment divided by squared variance) % of a matrix.  Kurtosis of a Gaussian distribution is 3.%  MEAN (optional) and VAR (optional) make the computation faster.% Eero Simoncelli, 6/96.function res = kurt2(mtx, mn, v)if (exist('mn') ~= 1)	mn =  mean(mean(mtx));endif (exist('v') ~= 1)	v =  var2(mtx,mn);endif (isreal(mtx))  res = mean(mean(abs(mtx-mn).^4)) / (v^2);else  res = mean(mean(real(mtx-mn).^4)) / (real(v)^2) + ...      i*mean(mean(imag(mtx-mn).^4)) / (imag(v)^2);end