fast matrix multiplication in Matlab

Question

I need to make a matrix/vector multiplication in Matlab of very large sizes: \"A\" is an 655360 by 5 real-valued matrix that are not necessarily sparse and \"B\" is a 655360

Answer 1

In order to avoid the transpose operation, you could try:

sum(bsxfun(@times, A, B), 2)

But I would be astonished it was faster than the direct version. See @thiton's answer.

Also look at http://www.mathworks.co.uk/company/newsletters/news_notes/june07/patterns.html to see why the column-vector-based version is faster than the row-vector-based version.