Efficiently compute a 3D matrix of outer products - MATLAB

This is just a minor improvement over Divakar's answer. It is a little faster because it replaces a 3D-array permute with a 2D-array permute:

B = bsxfun(@times, permute(A, [1 3 2]), permute(A, [3 1 2]));

To state the obvious, have you tried a simple for-loop:

[m,n] = size(A);
B = zeros(m,m,n);
for i=1:n
    B(:,:,i) = A(:,i) * A(:,i).';
end

You'll be surprised how competitively fast it is.

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