3D Matrix Multiplication

Hi I have created two large matrices of which I have reshaped to create the following:

A = 3x1x4 double
B = 3x3x4 double

C = B * A ????

I was wondering how I could multiply each 3x3 matrix from B with each 3x1 matrix from A? The aim is to create a new 3x1x4 matrix in the end. Note: I don't have R2020b so don't have access to the pagemtimes function.

Any help is greatly appreciated, thanks!

[Masoud Aminzadeh]

use pagewise function

Answer 1

[the cyclist]

You can do it straightforwardly with a for loop:

% Some made-up input data
A = rand(3,1,4);
B = rand(3,3,4);

[mA,nA,pA] = size(A);
[mB,nB,pB] = size(B);

C = zeros(mB,nA,pA);

for np = 1:pA
    C(:,:,np) = B(:,:,np) * A(:,:,np);
end

[Rahul Marwaha]

Thanks, that worked perfectly!

Answer 2

[Walter Roberson]

https://www.mathworks.com/matlabcentral/fileexchange/25977-mtimesx-fast-matrix-multiply-with-multi-dimensional-support

https://www.mathworks.com/matlabcentral/fileexchange/41663-multidimensional-matrix-multiplication

[James Tursa]

Also for R2020b and later

https://www.mathworks.com/help/matlab/ref/pagemtimes.html