[petsc-users] DMLocalToLocal with DMPlex in Fortran

[Matthew Knepley]

On Mon, Oct 10, 2022 at 10:41 PM Mike Michell <mi.mike1021 at gmail.com> wrote:

> Hi, I was wondering if there is any comment on the example file that I can
> refer to.
>

I see the problem. Local2Local is not implemented for Plex. I thought we
had this automated, but it was only
coded for DMDA. It is a fairly mechanical transformation of the
Global2Local, just remapping indices, but it
will take some time since there is a lot of backlog this semester.

I have fixed the error message so now it is obvious what the problem is.

  Thanks,

      Matt


> Thanks,
> Mike
>
>
>> Thank you for the reply.
>> Sure, a short example code is attached here with a square box mesh and a
>> run script.
>> Inside the source, you may find two versions of halo exchange; one is for
>> local to global (Version-1) and another one is for local to local
>> (Version-2), which is not working in my case.
>> In the output.vtu, you will see the halo exchanged vector resolved to
>> each vertex with (myrank + 1), so if the code is running with 2procs, at
>> the parallel boundary, you will see 3. In this example, there is no ghost
>> layer.
>>
>> Thanks,
>> Mike
>>
>>
>>> On Sat, Oct 1, 2022 at 8:51 PM Mike Michell <mi.mike1021 at gmail.com>
>>> wrote:
>>>
>>>> Thank you for the reply. There is that file in
>>>> src/dm/interface/ftn-auto/ for me, instead of the path you mentioned.
>>>>
>>>> After "make allfortranstubs" was done and, PETSc reconfigured and
>>>> reinstalled.
>>>>
>>>> However, I still have the same problem at the line in which
>>>> DMLocalToLocalBegin() is used. What I am doing to setup halo exchange is as
>>>> follows;
>>>> - declare DMPlex
>>>> - PetscSectionCreate()
>>>> - PetscSectionSetNumFields()
>>>> - PetscSectionSetFieldComponents()
>>>> - PetscSectionSetChart()
>>>> - do loop over dofs: PetscSectionSetDof() and PetscSectionSetFieldDof()
>>>> - PetscSectionSetUp()
>>>> - DMSetLocalSection()
>>>> - PetscSectionDestroy()
>>>> - DMGetSectionSF()
>>>> - PetscSFSetUp()
>>>>
>>>> Then, the halo exchange is performed as follows;
>>>> - DMGetLocalVector()
>>>> - Fill the local vector
>>>> - DMLocalToLocalBegin() --(*)
>>>> - DMLocalToLocalEnd()
>>>> - DMRestoreLocalVector()
>>>>
>>>> Then, the code crashes at (*).
>>>>
>>>
>>> Can you send something I can run? Then I will find the problem and fix
>>> it.
>>>
>>>   Thanks,
>>>
>>>      Matt
>>>
>>>
>>>> Previously(at the time PETSc did not support LocalToLocal for DMPlex in
>>>> Fortran), the part above, "DMLocalToLocalBegin() and DMLocalToLocalEnd()",
>>>> consisted of;
>>>> - DMLocalToGlobalBegin()
>>>> - DMLocalToGlobalEnd()
>>>> - DMGlobalToLocalBegin()
>>>> - DMGlobalToLocalEnd()
>>>> and it worked okay.
>>>>
>>>> I am unclear which part is causing the problem. Shall I define the
>>>> PetscSection and PetscSF in different ways in case of Local to Local Halo
>>>> exchange?
>>>> Any comment will be appreciated.
>>>>
>>>> Thanks,
>>>> Mike
>>>>
>>>>
>>>>
>>>>> On Fri, Sep 30, 2022 at 4:14 PM Mike Michell <mi.mike1021 at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> As a follow-up to this email thread,
>>>>>> https://www.mail-archive.com/petsc-users@mcs.anl.gov/msg44070.html
>>>>>>
>>>>>> Are DMLocalToLocalBegin() and DMLocalToLocalEnd() really available
>>>>>> for DMPlex with Fortran on the latest version of PETSc (3.17.99 from
>>>>>> GitLab)? Matt commented that the Fortran bindings were updated so that
>>>>>> those functions must be available in the latest version of PETSc, however,
>>>>>> it seems still they are not working from my test with DMPlex in Fortran.
>>>>>> Can anyone provide some comments? Probably I am missing some mandatory
>>>>>> header file? Currently, I have headers;
>>>>>>
>>>>>> #include "petsc/finclude/petscvec.h"
>>>>>> #include "petsc/finclude/petscdmplex.h"
>>>>>> #include "petsc/finclude/petscdmlabel.h"
>>>>>> #include "petsc/finclude/petscdm.h"
>>>>>>
>>>>>
>>>>> The source for these functions is in
>>>>>
>>>>>   src/dm/ftn-auto/dmf.c
>>>>>
>>>>> Is it there for you? If not, you can run
>>>>>
>>>>>   make allfortranstubs
>>>>>
>>>>> Fortran functions are not declared, so the header should not matter
>>>>> for compilation, just the libraries for linking.
>>>>>
>>>>>   Thanks,
>>>>>
>>>>>      Matt
>>>>>
>>>>>
>>>>>> Thanks,
>>>>>> Mike
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> 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/>
>>>>>
>>>>
>>>
>>> --
>>> 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/>
>>>
>>

-- 
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/>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20221011/7b7fc028/attachment.html>