MATLAB: Sum over a dimension

sum over dimension

Hi,
I try to sum over the third dimension of a matrix A, say A = ceil(5*rand(4,4,3)).
The third dimension equals variation in time. For t= 0 I want to have A(:,:,1); for t= 1 I want to have A(:,:,1) + A(:,:,2); for t=3 I want to have A(:,:,1) + A(:,:,2) + A(:,:,3).
The code below works, however, I want to do it without for-loops. Can someone help me? 
 [nr, nc, nd]= size(A)
for i=1:nd
for ii= 1:nr
for jj=1:nc
B(ii,jj,i) = sum(reshape(A(ii,jj,[1:i]),i,1)));
end
end
end

Best Answer

B = cumsum(A,3)
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