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Re: How can I compute condition number

To: petsc-users@xxxxxxxxxxx
Subject: Re: How can I compute condition number
From: "Matthew Knepley" <knepley@xxxxxxxxx>
Date: Sun, 24 Sep 2006 11:10:45 -0500
Cc: "Gong Ding" <gdiso@xxxxxxxx>
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On 9/24/06, Gong Ding <gdiso@xxxxxxxx> wrote:

Hi,
I meet some convergince problem with my
semiconductor simulation code. I 'd like to check
the condition number of Jacobian matrix. How can I
do with PETSC?

The true L_2 condition number would involve a very large
SVD calculation, and thus is rarely computed. We do have
the option:

-ksp_compute_singularvalues

which will give you the condition number of the Krylov matrix,
a low-dimensional approximation of your matrix. A very
convenient form of this is:

-ksp_singmonitor

which includes this information in the KSP monitor.

Thanks,

Matt

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