Rick, I have been experimenting with setting all the elements of larger matrices to a constant and I can't understand why x=j(100, 1, 0) * j(1, 30, 0) is around 4 times faster than j(100, 30, 0), and incidentally a little faster than the empty subscripts method. How can making one 3000 element array and filling with zero take longer than the creation of 3130 elements in 3 arrays plus the overhead of all the multiplications?