cumsum but withe the twelfth observation

I am using monthly data in twelfth difference (annuel variation) and for the final results I want to come back the level. I know that for the first différence we can use the cumsum function: cumsum(X(i,:,:),2)

How can I do the same think to cumulate the twelfth difference. Thanks

[Azzi Abdelmalek]

Can you explain with an example?

[Zak]

I wrote this code which works well with matrix, but not in the general case. I mean when the input is an array it doesn't work. "cumsum" function works even when the input is an array

[line col] = size(x); result = zeros(line,col);

for j=13:col; for i=1:line; result(i,1:12) = x(i,1:12); result(i,j) = result(i,j-12) + x(i,j); end; end;

Answer 1

[Julius]

Just do cumsum repeatedly for 12 times.