Sum of selected elements in Matrix

Hello,

For example, I have a 10x10 matrix. I need to find 1x1, 2x2, 3x3, 4x4 ... matrixes element sum, I couldn't find an answer with the sum command. Could you help.

Example;

Answer 1

[Alan Stevens]

How about:

for i=1:10, S(i) = sum(sum(A(1:i,1:i))); end

where A is your 10x10 matrix and S contains the 10 sums.

Answer 2

[Bruno Luong]

A=rand(1000);

[m,n]=size(A);
G=max((1:m)',1:n);
s=cumsum(accumarray(G(:),A(:)))