Multiply a 3D matrix with a 2D matrix

Question

Suppose I have an AxBxC matrix X and a BxD matrix Y.

Is there a non-loop method by which I can multiply

Answer 1

I highly recommend you use the MMX toolbox of matlab. It can multiply n-dimensional matrices as fast as possible.

The advantages of MMX are:

1. It is easy to use.
2. Multiply n-dimensional matrices (actually it can multiply arrays of 2-D matrices)
3. It performs other matrix operations (transpose, Quadratic Multiply, Chol decomposition and more)
4. It uses C compiler and multi-thread computation for speed up.

For this problem, you just need to write this command:

C=mmx('mul',X,Y);

here is a benchmark for all possible methods. For more detail refer to this question.

    1.6571 # FOR-loop
    4.3110 # ARRAYFUN
    3.3731 # NUM2CELL/FOR-loop/CELL2MAT
    2.9820 # NUM2CELL/CELLFUN/CELL2MAT
    0.0244 # Loop Unrolling
    0.0221 # MMX toolbox  <===================