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From: GS &lt;gshy2014@gamil.com&gt;
Newsgroups: comp.soft-sys.matlab
Subject: sparse matrix multiplication and cgs()
Date: Mon, 01 Jun 2009 11:19:26 EDT
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Hello, 
   I solved Ax=b, A is large(of size 2e5), sparse(each row has no more than 26 nonzero), symmetric positive definite matrix. I did it in two ways, 
1) L=chol(A,'lower'); tic, x=L\(L'\b),toc;
2) tic,[x,flag,resrel,iter]=cgs(A,b,[],n,[],[],x0),toc;

L is dense, iter=6. So theoretical 2) should be must faster than 1). But 1), 2) ends up with the same time.
Why?
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