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From: "Bruno Luong" <b.luong@fogale.findmycountry>
Newsgroups: comp.soft-sys.matlab
Subject: Re: adding order matters for accuracy ?
Date: Fri, 18 Sep 2009 06:55:25 +0000 (UTC)
Organization: FOGALE nanotech
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"Steven Lord" <slord@mathworks.com> wrote in message <h8u14i$1oe$1@fred.mathworks.com>...
> 
> "Bruno Luong" <b.luong@fogale.findmycountry> wrote in message 
> news:h8tuq7$qpr$1@fred.mathworks.com...
> 
> *snip*
> 
> > As a final note, the SUM went multithread lately, and the sum order can no 
> > longer straight forward predicted (in one experiment on my PC, this 
> > happens with array larger than 88998 elements). The same code can give 
> > then different result when running on different computer just because of 
> > this reason.
> 
> That was a bug that was fixed in the latest release:
> 
> http://www.mathworks.com/support/bugreports/532399
> 

Thank you for the info Steve. Indeed I played around witth SUM under 2009B by varying maxNumCompThreads (the soon-to-be-deleted command) and the result is consistent. When using on large array the behavior of SUM command has changed from previous Matlab versions. In short: it is no longer backward compatible. A small issue, nevertheless worth to notice.

Bruno