MATLAB: How to increment matrix elements using vectors of indexes

Question

Suppose I have matrix A and vectors M,N of indexes.

I want to increment every element in A according to the pairs of M & N.

I have tried:

A(M,N) = A(M,N) + 1;

The problem is that when a pair of indexes occurs more than once I get incrementation of only 1.

for example:

A = zeros(2,2);
M = [1 1]
N = [1 1]
A(M,N) = A(M,N) + 1;

The result is:

[1 0
 0 0]

instead of:

[2 0
 0 0]

Any solution??

Thanks, Eli.

Answer 1

A = A + accumarray([M(:),N(:)],1,size(A));