[petsc-dev] Right-preconditioned GMRES

[Matthew Knepley]

On Thu, Feb 9, 2017 at 7:06 AM, Pierre Jolivet <pierre.jolivet at enseeiht.fr>
wrote:

>
> On Feb 9, 2017, at 1:37 PM, Matthew Knepley <knepley at gmail.com> wrote:
>
> On Thu, Feb 9, 2017 at 4:56 AM, Pierre Jolivet <pierre.jolivet at enseeiht.fr
> > wrote:
>
>> Hello,
>> I _might_ be doing something wrong when calling
>> KSPSetFromOptions/KSPSetUp, but still, am I supposed to get this kind of
>> error?
>> [0]PETSC ERROR: No support for this operation for this object type
>> [0]PETSC ERROR: KSP gmres does not support PRECONDITIONED with RIGHT
>>
>> If not, I’ll try to send a MWE (it basically depends on where I set the
>> option -ksp_pc_side right).
>>
>
> I believe its telling you that it cannot display the preconditioned
> residual with right preconditioning, which is true.
> Are you requesting both?
>
>
> No, I’m just using -ksp_view and -ksp_pc_side right. In the “standard”
> case, it obviously work.
> However, the error is triggered if I set -ksp_pc_side right after a first
> call to KSPSetOperators()/KSPSetUp() without destroying the KSP.
> Should I destroy my KSP before changing from left- (default) to
> right-preconditioning if KSPSetOperators()/KSPSetUp has already been called?
>

Its likely you have to use


http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPSetNormType.html

or

  *-ksp_norm_type unpreconditioned*

since we would not have a chance to change it since its been set already.

  Thanks,

     Matt

Thanks.
>
>   Thanks,
>
>      Matt
>
>
>> Thanks,
>> Pierre
>
>
>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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