whether do I need to consider the symmetric preconditioner when using CG?

[Yujie]

Dear Lisandro:

>From PETSc manual, I know KSPCG only supports left preconditioning. However,
I want to know whether does this affect the performance of preconditioned
CG? The main problem is that it should be better to generate a symmetric
preconditioned operator for CG method. However, Left preconditioner should
have some difficulty to get such operator? Do you have any testings about it
regarding left, split and right preconditinoers and CG realization in
PETSc? thanks a lot.

Regards,
Yujie

On 1/16/08, Lisandro Dalcin <dalcinl at gmail.com> wrote:
>
> KSPCG only supports left preconditioning.
>
> On 1/16/08, Yujie <recrusader at gmail.com> wrote:
> > hi, everyone
> >
> > I know there are three types of preconditioners, that is left, split and
> > right preconditioners? When I use CG method in PETSc, whether do I need
> to
> > consider select one type of preconditioner? Whether do different types
> > affect the performance of preconditioned CG? thanks a lot.
> >
> > Regards,
> > Yujie
> >
>
>
> --
> Lisandro Dalcín
> ---------------
> Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
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>
>
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