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Slow sparse matrix multiplication
From: |
Richard Hindmarsh |
Subject: |
Slow sparse matrix multiplication |
Date: |
Wed, 9 Mar 2005 15:52:40 -0600 |
User-agent: |
Mozilla/5.0 (Windows; U; WinNT4.0; en-US; rv:1.7.1) Gecko/20040707 |
Matrix-matrix multiplication for very sparse matrices seems a bit slow.
The results below apply also to very sparse matrix/vector multiplications.
CVS downloaded 9th March 2005, x86-64, gcc3.3.2
octave:17> a = sparse(10000,10000);
octave:18> a(1,1) = 1;
octave:19> tic;a*a;toc
ans = 0.73152
octave:20> tic;a+a;toc
ans = 0.00047300
Given that the number of f.p. operations are the same, one would expect
similar timings. I'd be happy to have a look at the matrix
multiplication routines if pointed too them.
Richard
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- Slow sparse matrix multiplication,
Richard Hindmarsh <=