samer@4: function y=rotl(x,n)
samer@4: % rotl - rotate columns of array to left
samer@4: %
samer@4: % rotl :: [[N,M]] -> [[N,M]].
samer@4: % rotl :: [[N,M]], natural -> [[N,M]].
samer@4: 
samer@4: if nargin<2, n=1; end
samer@4: y = x(:,[n+1:size(x,2),1:n]);