[petsc-users] about linear solver convergence

[behzad baghapour]

Thanks and what means if they are the same in ksp iterations?

On Tue, Oct 11, 2011 at 7:08 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> On Tue, Oct 11, 2011 at 10:33, behzad baghapour <
> behzad.baghapour at gmail.com> wrote:
>
>> What is the difference between "unpreconditioned resid norm"
>
>
> This is estimated implicitly using the Krylov iteration. It can become
> inaccurate if the Krylov basis loses orthogonality (an issue of numerical
> stability).
>
>
>> and "true resid norm" in -ksp_monitor?
>
>
> This builds the residual explicitly. It is expensive with some methods,
> e.g. GMRES.
>



-- 
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Behzad Baghapour
Ph.D. Candidate, Mechecanical Engineering
University of Tehran, Tehran, Iran
https://sites.google.com/site/behzadbaghapour
Fax: 0098-21-88020741
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