Hi was just wondering if anybody could help me understand convolution of a matrices. I'm asked to compute the convolution of A and B where

A = [-3 1 3] and B = [2 1 3 1 2]

apprently the answer is (-2/7 3/7 4/7) , but i have no clue how to get there, can't seem to find a good tutorial on convolution anywhere, any help would be much appreciated thanks : )