Drexel dragonThe Math ForumDonate to the Math Forum


Math Forum
 Ask Dr. Math
 Discussions
 Internet Newsletter
 MathTools
 Problems of the Week
 Teacher2Teacher
 Teacher Exchange
 Workshops

Search All of the Math Forum:
Browse our Internet Mathematics Library

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » Software » comp.soft-sys.matlab

Topic: speeding up ACCUMARRAY
Replies: 12   Last Post: Nov 15, 2012 3:35 AM

Advanced Search
Reply to this Topic Reply to this Topic

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Bruno Luong

Posts: 8,461
Registered: 7/26/08
Re: speeding up ACCUMARRAY
Posted: Nov 14, 2012 2:52 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

"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 multi-threading, and other low-level optimization.

Accumarray is not slow. Just sparse is fast.

Bruno

Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2013. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.