[petsc-users] Only print converged reason when not converged

[Alexander Lindsay]

The only slight annoyance with doing this through a PostSolve hook as
opposed to a pluggable ReasonView system is that if a user passed
`-snes_converged_reason` on the command line, we would get redundant
printout from SNESSolve and our PostSolve. Although I suppose we could
solve this by intercepting their option, not passing it to PETSc, and then
just using that info to control the output from our PostSolve (e.g. if a
user passes -snes_converged_reason from the command line, then we should
always print the reason, instead of just printing when we don't converge).
So maybe the PostSolve will work fine.

On Tue, Jul 28, 2020 at 12:20 PM Barry Smith <bsmith at petsc.dev> wrote:

>
>   KPSSetPostSolve(),  There is no SNESSetPostSolve()  but there
> could/should be.
>
>    Barry
>
>   Note inside the SNESSolve there are a bunch of pre and post hooks, don't
> get the confused with an outside SNESSetPostSolve()
>
> On Jul 28, 2020, at 1:12 PM, Fande Kong <fdkong.jd at gmail.com> wrote:
>
> One alternative is to support a plugable KSP/SNESReasonView system. We
> then could hook up KSP/SNESReasonView_MOOSE.
>
> We could call our views from SNES/KSP"done"Solve as well if such a
> system is not affordable.  What are the final functions we should call,
> where we guarantee SNES/KSP is already done?
>
> Thanks,
>
> Fande,
>
> On Tue, Jul 28, 2020 at 12:02 PM Barry Smith <bsmith at petsc.dev> wrote:
>
>>
>>   Alex,
>>
>>     The actual printing is done with SNESReasonView() and KSPReasonView()
>> I would suggest copying those files to Moose with a name change and
>> removing all the code you don't want. Then you can call your versions
>> immediately after SNESSolve() and KSPSolve().
>>
>>    Barry
>>
>>
>> > On Jul 28, 2020, at 10:43 AM, Alexander Lindsay <
>> alexlindsay239 at gmail.com> wrote:
>> >
>> > To help debug the many emails we get about solves that fail to
>> converge, in MOOSE we recently appended `-snes_converged_reason
>> -ksp_converged_reason` for every call to `SNESSolve`. Of course, now we
>> have users complaining about the new text printed to their screens that
>> they didn't have before. Some of them have made a reasonable request to
>> only print the convergence reason when the solve has actually failed to
>> converge. Is there some way we can only print the reason if we've diverged,
>> e.g. if reason < 0 ?
>> >
>> > Alex
>>
>>
>
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