Operation on 3 dimension matrix

Hi I have two 3-dimension matrices A(N,M,P) and B(M,N,P). I want to calculate the multiplication along two dimensions, that is

       for ii=1:P
        C(:,:,ii) = A(:,:,ii)*B(:,:,ii);
       end

Is there any solution to achieve the above computation without for loop?

Thanks

Rui

Answer 1

[Image Analyst]

How about this:

C = A .* B;

[Image Analyst]

My answer is for element by element multiplication, like masking an image or something, not row times column "matrix" multiplication. Can you confirm that you want matrix multiplication, where C(1,2,1) = sum(A(1,:,1) .* B(:,2,1), and not something like C(1,2,1) = A(1,2,1)*B(1,2,1)?

Answer 2

[Jan]

Why do you want to do this without a loop? The main work is spent with tha matrix multiplication. Even a vectorized version cannot reduce this work.

But a parallelization can distribute the job. Do you have the Parallel Processing Toolbox? Then use parfor.

You can try these alternative tools:

• FEX: mtimesx
• FEX: mmx

[James Tursa]

Also this one:

http://www.mathworks.com/matlabcentral/fileexchange/8773-multiple-matrix-multiplications--with-array-expansion-enabled