size(M,1) % The number or rows of an array.
size(M,2) % The number of columns of an array.
also,
S = size(M);
S(1) % The same as size(M,1)
S(2) % The same as size(M,2)
In general,
A = rand(4,5,2,2);
S = size(A)
notice the connection between S and the argument to RAND.
