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Re: large sparse matrix


From: Carlo de Falco
Subject: Re: large sparse matrix
Date: Tue, 1 Sep 2009 10:12:12 +0200


On 1 Sep 2009, at 10:04, Carlo de Falco wrote:

2009/9/1 Carlo de Falco <address@hidden>:

Also, what does the code

[R, p, q] = chol(A);
nnz(R)


work for Octave and Matlab?

I tried this in Octave, after 30 min it did not finish yet...
I will only be able to try it on Matlab tomorrow.

If so what is the value of NNZ of the factorization in both cases.

I killed the Octave after it had been running more than one hour and
produced no result.
In Matlab it ran in less than a second and the result was:

[R,p,q]=chol(A);
nnz (R)
ans =
    1368019
issparse (R)
ans =
    1
nnz(R)/prod(size(A))
ans =
    7.035863106552923e-03

oops, what I actually meant to show here was

>> nnz(R)/prod(size(R))
ans=
   1.407374482251814e-02

Thanks,
c.



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