Y = colshift(X, S) circularly shifts the elements in the k-th column of
the matrix X by S(k) positions. If S(k) is positive, then the values of
X are circularly shifted from the beginning to the end. If S(k) is
negative, they are shifted from the end to the beginning.
If S is a scalar, each column is shifted by the amount S.

Example:
X = [ 1 11 21
2 12 22
3 13 23
4 14 24 ]
Y = colshift(X, [2 0 -1])
% -> [ 3 11 22
4 12 23
1 13 24
2 14 21 ]

See also circshift