Hello list! I've got a question concerning matrix operations. I'd like to fill a numpy-array (A) with values. for j in range(maxj): for i in range(maxi): y = i / 4 x = j / 4 index = (j - j / 4 * 4) * 4 + (i - i / 4 * 4) if index == xyz: C = C1 elif index == xyz +1: C = C2 elif ....... ....... A[j,i] = sum( sum( B[ x-r:x+2 , y-s:y+2 ] * C ) ) C, s, r are depending on index; x and y are depending on i and j. The problem is that it takes to long this way. Is it possible to do this without iterarting with numpy? Thanks for your help! Greetings Maik