[petsc-users] Inquiry about metric-based adaptation using MMG in petsc

[Matthew Knepley]

On Sun, Sep 15, 2024 at 7:25 AM neil liu <liufield at gmail.com> wrote:

> Thanks a lot, Jed.
> I traced  the code and found the following issues,
> 1) in *PetscErrorCode DMPlexMetricNormalize(DM dm, Vec metricIn,
> PetscBool restrictSizes, PetscBool restrictAnisotropy, Vec metricOut, Vec
> determinant),*
> the metricIn is zero
> *. And this seems not reasonable. *
> *Go back to,*
> 2) DMAdaptorAdapt_Sequence_Private(DMAdaptor adaptor, Vec inx, PetscBool
> doSolve, DM *adm, Vec *ax)
> with -sol_adapt_loc_pre_view, -adapt_gradient_view and
> -adapt_hessian_view, all these three vectors are zero.
> This is not reasonable.
>
> *Go back to, *
> *3) *PetscErrorCode DMAdaptorAdapt(DMAdaptor adaptor, Vec x,
> DMAdaptationStrategy strategy, DM *adm, Vec *ax)
>     x is zero here.
> Go back to,
> *4)  *PetscCall(SNESSolve(snes, NULL, u));
> The initial guess u is zero. It seems this is the reason. A little weird.
> An intiial guess with zero should be resonable.
>
> It seems maybe something is not reasonable for the logic in
> *DMPlexMetricNormalize.*
>

Is the solve not doing anything? We need at least one solution in order to
adapt. Did you look at SNES ex27? I adaptively refine that one.

  Thanks,

   Matt


> *Thanks,*
>
>
> *Xiaodong *
>
>
>
>
>
>
>
> On Fri, Sep 13, 2024 at 2:22 PM Jed Brown <jed at jedbrown.org> wrote:
>
>> This error message is coming from the following:
>>
>> $ rg -B4 'Global metric normalization factor must be in'
>> src/dm/impls/plex/plexmetric.c
>> 1308-    PetscCall(PetscDSSetObjective(ds, 0, detMFunc));
>> 1309-    PetscCall(DMPlexComputeIntegralFEM(dmDet, determinant,
>> &integral, NULL));
>> 1310-  }
>> 1311-  realIntegral = PetscRealPart(integral);
>> 1312:  PetscCheck(realIntegral > 1.0e-30, PETSC_COMM_SELF,
>> PETSC_ERR_ARG_OUTOFRANGE, "Global metric normalization factor must be in
>> (0, inf). Is the input metric positive-definite?");
>>
>> Perhaps you can independently check what integrand is being provided.
>> It's probably zero or negative. You could apply this patch so the error
>> message will report a value.
>>
>>
>> diff --git i/src/dm/impls/plex/plexmetric.c
>> w/src/dm/impls/plex/plexmetric.c
>> index 61caeed28de..906cb394027 100644
>> --- i/src/dm/impls/plex/plexmetric.c
>> +++ w/src/dm/impls/plex/plexmetric.c
>> @@ -1309,7 +1309,7 @@ PetscErrorCode DMPlexMetricNormalize(DM dm, Vec
>> metricIn, PetscBool restrictSize
>>      PetscCall(DMPlexComputeIntegralFEM(dmDet, determinant, &integral,
>> NULL));
>>    }
>>    realIntegral = PetscRealPart(integral);
>> -  PetscCheck(realIntegral > 1.0e-30, PETSC_COMM_SELF,
>> PETSC_ERR_ARG_OUTOFRANGE, "Global metric normalization factor must be in
>> (0, inf). Is the input metric positive-definite?");
>> +  PetscCheck(realIntegral > 1.0e-30, PETSC_COMM_SELF,
>> PETSC_ERR_ARG_OUTOFRANGE, "Global metric normalization factor %g must be in
>> (0, inf). Is the input metric positive-definite?", (double)realIntegral);
>>    factGlob = PetscPowReal(target / realIntegral, 2.0 / dim);
>>
>>    /* Apply local scaling */
>>
>>
>> neil liu <liufield at gmail.com> writes:
>>
>> > Dear Petsc developers and users,
>> >
>> > I am  trying to explore adaptive mesh refinement (tetradedra) with
>> Petsc.
>> > It seems case 12 ($PETSC DIR/src/snes/tutorials/ex12.c, from paper,
>> >
>> https://urldefense.us/v3/__https://arxiv.org/pdf/2201.02806__;!!G_uCfscf7eWS!ZEwaHkvYc_IrjycFr8LiNi-nZcFqu0ZpsydAAomxptQ6C0xkBs3qhn5ba31Z4vipKf4mTrqDm8A5S65DDD_xFg$
>> ) is a good example.
>> > However when I tried,
>> > ./ex12 -run_type full -dm_plex_dim 3 -dm_distribute -dm_plex_box_faces
>> > 10,10,10 -bc_type dirichlet -petscspace_degree 1 -variable_coefficient
>> ball
>> > -snes_converged
>> > _reason ::ascii_info_detail -ksp_type cg -pc_type sor
>> -snes_adapt_sequence
>> > 3 -adaptor_target_num 1000 -dm_plex_metric_h_max  0.5  -dm_adaptor mmg
>> >       L_2 Error: 1.55486
>> >       Nonlinear solve converged due to CONVERGED_FNORM_RELATIVE
>> iterations 2
>> >
>> > it shows the following error,
>> > [0]PETSC ERROR: --------------------- Error Message
>> > --------------------------------------------------------------
>> > [0]PETSC ERROR: Argument out of range
>> > [0]PETSC ERROR: Global metric normalization factor must be in (0, inf).
>> Is
>> > the input metric positive-definite?
>> >
>> > Do  you have any suggestions here?
>> >
>> > Thanks,
>> >
>> > Xiaodong
>>
>

-- 
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://urldefense.us/v3/__https://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!djDLOY8Rh_OQw8vhb4B7V0-zm0LToQcf2kEcTsKIYyUymnyy49THra-UsRtW-B_YH1Fm5t5I2bSpjfhAEoLt$  <https://urldefense.us/v3/__http://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!djDLOY8Rh_OQw8vhb4B7V0-zm0LToQcf2kEcTsKIYyUymnyy49THra-UsRtW-B_YH1Fm5t5I2bSpjQQ58Sqe$ >
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20240915/e60ac22b/attachment-0001.html>