MATLAB: Multiply two 3D arrays that result would be 4D

Question

Hello to All,

I am trying to work and understand 4D arrays. Lets say I have two 3D gpuArrays a(100x5x5) and b(5x5x5). I would like to multiply them that it would result in 4D array c(100x5x5x5), and example of multiplication:

For j=1:5
For i=1:5
c(:,:,i,j)=a(:,i,j)*b(i,:,j)
end
end

What would be the way to achieve this. I am trying to go for 4D arrays, because I would like to avoid for loops.

Answer 1

Assuming I understand what you are trying to do,

result = permute(a,[1 4 2 3]) .* permute(b,[4 2 1 3]);

or in earlier versions of MATLAB

result = bsxfun(@times,permute(a,[1 4 2 3]) , permute(b,[4 2 1 3]));