# multiTimes

## PURPOSE

Matrix multiply each submatrix of two 3D arrays without looping.

## SYNOPSIS

function C = multiTimes( A, B, type )

## DESCRIPTION

     Matrix multiply each submatrix of two 3D arrays without looping.

     type controls the matrix multiplication to perform (for each i):
      1    - C(:,:,i) = A(:,:,i)*B(:,:)
      1.1  - C(i,:,:) = A(:,:,i)*B(:,:)
      1.2  - C(:,:,i) = A(:,:)*B(:,:,i)
      2    - C(:,:,i) = A(:,:,i)*B(:,:,i)
      2.1  - C(:,:,i) = A(:,:,i)'*B(:,:,i)
      2.2  - C(:,:,i) = A(:,:,i)*B(:,:,i)'
      3    - C(:,i) = A(:,:,i)*B(:,i)
      3.1  - C(:,i) = A(:,:,i)'*B(:,i)
      3.2  - C(:,i) = A(:,i)'*B(:,:,i)
      3.3  - C(:,i) = A(:)'*B(:,:,i)
      4.1  - C(i) = trace(A(:,:,i)'*B(:,:,i))
     Corresponding dimensions of A and B must match appropriately.

     USAGE
      C = multiTimes( A, B, type )

     INPUTS
      A         - [ma x na x oa] matrix
      B         - [mb x nb x ob] matrix
      type      - multiplication type (see above)

     OUTPUTS
      C         - result of the multiplication

     EXAMPLE
      n=10000; A=randn(2,2,n); B=randn(2);
      tic, C1=multiTimes(A,B,1); toc
      tic, C2=zeros(size(A)); for i=1:n, C2(:,:,i)=A(:,:,i)*B; end; toc

     See also BSXFUN, MTIMES

     Piotr's Image&Video Toolbox      Version 2.42
     Copyright 2010 Piotr Dollar.  [pdollar-at-caltech.edu]
     Please email me if you find bugs, or have suggestions or questions!
     Licensed under the Lesser GPL [see external/lgpl.txt]

## CROSS-REFERENCE INFORMATION

This function calls:

This function is called by: