[petsc-users] Fortran: PetscDSRestoreTabulation + PetscDSGetTabulation

[Matthew Knepley]

On Thu, Aug 29, 2024 at 9:57 AM Martin Diehl <martin.diehl at kuleuven.be>
wrote:

> Dear PETSc team,
>
> I have a question regarding the use of PetscDSGetTabulation from
> Fortran.
> PetscDSGetTabulation has a slightly different function signature
> between Fortran and C. In addition, there is an (undocumented)
> PetscDSRestoreTabulation in Fortran which cleans up the arrays. Calling
> it results in a segmentation fault.
>
> I believe that PetscDSRestoreTabulation is not needed. At least our
> Fortran FEM code compiles and runs without it. However, we have
> convergence issues that we don't understand so any suspicious code is
> currently under investigation.
>

This may be due to my weak Fortran knowledge. Here is the code


https://urldefense.us/v3/__https://gitlab.com/petsc/petsc/-/blob/main/src/dm/dt/interface/f90-custom/zdtdsf90.c?ref_type=heads__;!!G_uCfscf7eWS!dBU6FLrC9bckJQhQgaPX-SxZbtbXKaPqvirTeDpSB_7r8Pn1M2Lo4ZkCq70i-eFj3KAT-qA_gjQDfjsxLbf2$ 

I call F90Array1dCreate() in the GetTabulation and F90Array1dDestroy() in
the RestoreTabulation(), which I thought
was right. However, I remember something about interface declarations,
which have now moved somewhere I cannot find.

Barry, is the interface declaration for this function correct?

  Thanks,

      Matt


> best regards,
> Martin
>
> --
> KU Leuven
> Department of Computer Science
> Department of Materials Engineering
> Celestijnenlaan 200a
> 3001 Leuven, Belgium
>
>

-- 
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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