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

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

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Matt J

Posts: 4,976
Registered: 11/28/09
Re: speeding up ACCUMARRAY
Posted: Nov 14, 2012 9:58 AM
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"Bruno Luong" <b.luong@fogale.findmycountry> wrote in message <k7vfli$da4$1@newscl01ah.mathworks.com>...
> "Matt J" wrote in message <k7ulhl$iod$1@newscl01ah.mathworks.com>...
>
> >In fact, the sparse matrix multiplication is probably even handicapped relative to accumarray, since it has to search through x for the appropriate x(J),
>
> There is no such step in sparse multiplication.
=============

Meaning that y=A*x is generated by looping over columns of A instead of rows? Even if so, how would that explain the speed difference?

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