samer@4: function R=minmax(X,I)
samer@4: % minmax - return minimum and maximum along a particular dimension
samer@4: %
samer@4: % minmax :: [[N,M]], 1:natural -> [[2,M]].
samer@4: % minmax :: [[N,M]], 2:natural -> [[N,2]].
samer@4: % minmax :: [D:[[1,E]]], I:[E] -> [set(D,I,2)].
samer@4: %
samer@4: % The most general type means that the return array is the same size
samer@4: % as the input array except that the size along the Ith dimension
samer@4: % becomes 2, first element is min, second is max.
samer@4: % 
samer@4: % The functions is constructed so that it is idemponent:
samer@4: %   minmax(X,I) == minmax(minmax(X,I),I)
samer@4: 
samer@4: R= cat(I,min(X,[],I),max(X,[],I));