MATLAB: Vector to repeated matrix multiplication

matrix vector element multiplication and summing

Hi all.

Just wanted to find a non loop way of computing the following operation.

A = [1 2; 3 4], V = [ 1 2 3]

compute Y = 1*A + 2*A + 3*A = 1*[1 2; 3 4] + 2*[1 2; 3 4] + 3*[1 2; 3 4] = [6 12; 18 24]

i.e. each element of V times A then sum up each of these matrices

many thanks!

One approach:

sum(bsxfun(@times,A,reshape(V,1,1,3)),3)

v1 = [0 1 2 3], 
v2 = [0 1 2]
[a,b]=ndgrid(v1,v2)
out=[a(:) b(:)]

   a=1:10000000;
  b=repmat(3,size(a));
  tic
  c1=a.^b;
  toc
  tic
  c2=a.^3;
  toc
  tic
  c3=a.*a.*a;
  toc

And then the results are,

 Elapsed time is 0.118509 seconds.
 Elapsed time is 0.129281 seconds.
 Elapsed time is 0.006726 seconds.