[petsc-users] Stop KSP if diverging

[Edoardo alinovi]

Thanks Matthew,

Yes, I will give it a try thid evening.

Thak you very much!

On Wed, 29 May 2019, 11:32 Matthew Knepley, <knepley at gmail.com> wrote:

> On Wed, May 29, 2019 at 3:07 AM Edoardo alinovi via petsc-users <
> petsc-users at mcs.anl.gov> wrote:
>
>> Dear PETSc friends,
>>
>> Hope you are doing all well.
>>
>> I have a quick question for you that I am not able to solve by my self.
>> Time to time, while testing new code features, it happens that KSP diverges
>> but it does not stop automatically and the iterations continue even after
>> getting a NaN.
>>
>
> I think you want
>
>
> https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPSetErrorIfNotConverged.html
>
>   Thanks,
>
>     Matt
>
>
>> In the KSP setup I use the following instruction to set the divergence
>> stopping criteria (div = 10000):
>>
>> call KSPSetTolerances(myksp,  rel_tol,  abs_tol, div,  itmax,  ierr)
>>
>> But is does not help. Looking into the documentation I have found also:
>>
>> KSPConvergedDefault <https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPConvergedDefault.html#KSPConvergedDefault>(KSP <https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSP.html#KSP> ksp,PetscInt <https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Sys/PetscInt.html#PetscInt> n,PetscReal <https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Sys/PetscReal.html#PetscReal> rnorm,KSPConvergedReason <https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPConvergedReason.html#KSPConvergedReason> *reason,void *ctx)
>>
>> Which I am not calling in the code. Is this maybe the reason of my
>> problem? If yes how can I use KSPConvergedDefault
>> <https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPConvergedDefault.html#KSPConvergedDefault> in
>> FORTRAN?
>>
>> Thanks,
>>
>> Edo
>>
>> ------
>>
>> Edoardo Alinovi, Ph.D.
>>
>> DICCA, Scuola Politecnica,
>> Universita' degli Studi di Genova,
>> 1, via Montallegro,
>> 16145 Genova, Italy
>>
>> Email: edoardo.alinovi at dicca.unige.it
>> Tel: +39 010 353 2540
>> Website: https://www.edoardoalinovi.com/
>>
>>
>>
>
> --
> 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
>
> https://www.cse.buffalo.edu/~knepley/
> <http://www.cse.buffalo.edu/~knepley/>
>
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