need to optimise my code

Hello friends,

i am writing a matlab optimisation program. Following is the segment of my code. for large value of m and n, this segment is taking longer time to execute. I want to optimise this code. Is there any body can help me in optimising this segment of code?

for s=1:m
    for i=1:n
        for j=1:n
            for k=1:n
                for l=1:n
                    A = A + D(k,l) * C(i,j,t) * B(i,k,s) * B(j,l,s);
                 end
            end
        end
    end
end

thanks in advance...:)

[Teja Muppirala]

Where did you come up with this? Is this just a direct translation from C or Fortran or something? This is probably just some simple matrix operation, but you've got it all written out in loops. Just like you did here:

http://www.mathworks.com/matlabcentral/answers/38829-about-nested-for-loop

Answer 1

[Andrei Bobrov]

See nice Teja' solution:

A = sum(arrayfun(@(ii)sum(sum(C(:,:,ii).*(B(:,:,ii)*D*B(:,:,ii)'))),1:size(C,3)))

if t ->s