3D Matrix Multiply

1. Assume a vector V which is (P X 1) array.
2. Assume matrices A,B which is (M X N X P) array.

I want to multiply A(i, j, :) .* V for each 0 < i <= M , and 0 < j <= N.

Currently I'm using loops to make it happen:

for ii = 1 : M

for jj = 1 : N

B(ii, jj, :) = V.* squeeze(A(ii, jj, :));

end

end

Is there any way to do so which doesn't include any use of loops?

[madhan ravi]

How about this?

a= rand(3,2,3); %M X N XP
V=rand(2,1); %P X 1

A=permute(a,[3 2 1]) 

 A(:,:,1) * V % V multiplied with first page?

Answer 1

[Jan]

B = A .* reshape(V, [1, 1, numel(V)])

This works with auto-expanding since R2016b.

[Nitai Fingerhut]

seems like it works!

thanks!

[Matt J]

@Nitai, you should Accept-click Jan's solution, since it solves your problem.

[Jan]

You are welcome. Matlab makes it easy to suggest such a compact and efficient solution.