
Re: speeding up ACCUMARRAY
Posted:
Nov 14, 2012 2:52 PM


"Matt J" wrote in message <k80l22$qd5$1@newscl01ah.mathworks.com>...
> > Anyway, my point remains. Sparse matrix multiplication has to perform multiplications with the x(j) somewhere, whereas accumarray, in my tests, does not. So sparse mult. is further handicapped.
1) Sparse internally access memory via integer indexing. Your accumarray has to cast doubles (firs input) to integers.
2) Sparse multiplication engine might benefice multithreading, and other lowlevel optimization.
Accumarray is not slow. Just sparse is fast.
Bruno

