MATLAB: Sum N many of the same array, which are each offset by an integer M

Question

I have an array A = [1; 2; 3; 2; 1] and I would like to make an new array B, which is equal to the sum of N many of A, where array N+1 is off set by M many interfers from array N.

Say N = 3 and M = 1, the new array would be B = [1+0+0; 2+1+0; 3+2+1, 2+3+2; 1+2+3; 0+1+2; 0+0+1].

I need A to be an array of any size and I would like to have control over the size of N and M. A will always be 1D in this case

I have attched a picutre of the problem excel. In one case M = 1 and the other M = 2. In both cases N = 3.

Thanks for any help you can offer

Answer 1

function B = movSum(A,n,m)
B=A;
for k=2:n
    B=[B;zeros(m,1)]+[zeros((k-1)*m,1);A];
end
end