[petsc-users] Configure nested PCFIELDSPLIT with general index sets

Thu May 4 09:17:33 CDT 2017

Dear Matt,
I re-checked the master branch. To be precise, I downloaded the nightly
tarball this morning (from
http://ftp.mcs.anl.gov/pub/petsc/petsc-master.tar.gz)
I am sure that the Fortran interface of DMSellSetCreateFieldDecomposition
is missing.
And it is quite tricky to add it. I have tried to write something in
src/dm/impls/shell/ftn-custom/zdmshellf.c but I am not familiar with
callbacks.
Any help would be greatly appreciated!
Best regards
Natacha

On Fri, Apr 28, 2017 at 8:11 PM, Matthew Knepley <knepley at gmail.com> wrote:

> On Fri, Apr 28, 2017 at 1:09 PM, Matthew Knepley <knepley at gmail.com>
> wrote:
>
>> On Fri, Apr 28, 2017 at 11:48 AM, Natacha BEREUX <
>> natacha.bereux at gmail.com> wrote:
>>
>>> Dear Matt,
>>> Sorry for my (very) late reply.
>>> I was not able to find the Fortran interface of
>>> DMSellSetCreateFieldDecomposition in the late petsc-3.7.6 fortran (and
>>> my code still fails to link).
>>> I have the feeling that it is missing in the master branch.
>>> And I was not able to get it on bitbucket either.
>>> Is there a branch from which I can pull your commit  ?
>>>
>>
>> I would either:
>>
>>   a) Use the 'next' branch
>>
>> or
>>
>>   b) wait until Monday for me to merge to 'master'
>>
>> This merge has been held up, but can now go forward.
>>
>
> I just checked master. It was already merged. Please recheck your master.
>
>   Thanks,
>
>      Matt
>
>
>>   Thanks,
>>
>>      Matt
>>
>>
>>> Thans a lot for your help,
>>> Natacha
>>>
>>> On Thu, Mar 30, 2017 at 9:25 PM, Matthew Knepley <knepley at gmail.com>
>>> wrote:
>>>
>>>> On Wed, Mar 22, 2017 at 1:45 PM, Natacha BEREUX <
>>>> natacha.bereux at gmail.com> wrote:
>>>>
>>>>> Hello Matt,
>>>>> Thanks a lot for your answers.
>>>>> Since I am working on a large FEM Fortran code, I have to stick to
>>>>> Fortran.
>>>>> Do you know if  someone plans to add this Fortran interface? Or may be
>>>>> I could do it myself ? Is this particular interface very hard to add ?
>>>>> Perhaps could  I mimic some other interface ?
>>>>> What would you advise ?
>>>>>
>>>>
>>>> I have added the interface in branch knepley/feature-fortran-compose.
>>>> I also put this in the 'next' branch. It
>>>> should make it to master soon. There is a test in
>>>> sys/examples/tests/ex13f
>>>>
>>>>   Thanks,
>>>>
>>>>     Matt
>>>>
>>>>
>>>>> Best regards,
>>>>> Natacha
>>>>>
>>>>> On Wed, Mar 22, 2017 at 12:33 PM, Matthew Knepley <knepley at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> On Wed, Mar 22, 2017 at 10:03 AM, Natacha BEREUX <
>>>>>> natacha.bereux at gmail.com> wrote:
>>>>>>
>>>>>>> Hello,
>>>>>>> if my understanding is correct, the approach proposed by Matt and
>>>>>>> Lawrence is the following :
>>>>>>> - create a DMShell (DMShellCreate)
>>>>>>> - define my own CreateFieldDecomposition to return the index sets I
>>>>>>> need (for displacement, pressure and temperature degrees of freedom) :
>>>>>>> myCreateFieldDecomposition(... )
>>>>>>> - set it in the DMShell ( DMShellSetCreateFieldDecomposition)
>>>>>>> - then sets  the DM in KSP context  (KSPSetDM)
>>>>>>>
>>>>>>> I  have some more questions
>>>>>>> - I did not succeed in setting my own CreateFieldDecomposition in
>>>>>>> the DMShell : link  fails with " unknown reference to «
>>>>>>> dmshellsetcreatefielddecomposition_ ». Could it be a Fortran
>>>>>>> problem (I am using Fortran)?  Is this routine available in PETSc  Fortran
>>>>>>> interface ? \
>>>>>>>
>>>>>>
>>>>>> Yes, exactly. The Fortran interface for passing function pointers is
>>>>>> complex, and no one has added this function yet.
>>>>>>
>>>>>>
>>>>>>> - CreateFieldDecomposition is supposed to return an array of dms (to
>>>>>>> define the fields). I am not able to return such datas.  Do I return a
>>>>>>> PETSC_NULL_OBJECT instead ?
>>>>>>>
>>>>>>
>>>>>> Yes.
>>>>>>
>>>>>>
>>>>>>> - do I have to provide something else to define the DMShell ?
>>>>>>>
>>>>>>
>>>>>> I think you will have to return local and global vectors, but this
>>>>>> just means creating a vector of the correct size and distribution.
>>>>>>
>>>>>>   Thanks,
>>>>>>
>>>>>>      Matt
>>>>>>
>>>>>>
>>>>>>> Thanks a lot for your help
>>>>>>> Natacha
>>>>>>>
>>>>>>> On Tue, Mar 21, 2017 at 2:44 PM, Natacha BEREUX <
>>>>>>> natacha.bereux at gmail.com> wrote:
>>>>>>>
>>>>>>>> Thanks for your quick answers. To be honest, I am not familiar at
>>>>>>>> all with DMShells and DMPlexes. But since it is what I need, I am going to
>>>>>>>> try it.
>>>>>>>> Thanks again  for your advices,
>>>>>>>> Natacha
>>>>>>>>
>>>>>>>> On Tue, Mar 21, 2017 at 2:27 PM, Lawrence Mitchell <
>>>>>>>> lawrence.mitchell at imperial.ac.uk> wrote:
>>>>>>>>
>>>>>>>>>
>>>>>>>>> > On 21 Mar 2017, at 13:24, Matthew Knepley <knepley at gmail.com>
>>>>>>>>> wrote:
>>>>>>>>> >
>>>>>>>>> > I think the remedy is as easy as specifying a DMShell that has a
>>>>>>>>> PetscSection (DMSetDefaultSection) with your ordering, and
>>>>>>>>> > I think this is how Firedrake (http://www.firedrakeproject.org/)
>>>>>>>>> does it.
>>>>>>>>>
>>>>>>>>> We actually don't use a section, but we do provide
>>>>>>>>> DMCreateFieldDecomposition_Shell.
>>>>>>>>>
>>>>>>>>> If you have a section that describes all the fields, then I think
>>>>>>>>> if the DMShell knows about it, you effectively get the same behaviour as
>>>>>>>>> DMPlex (which does the decomposition in the same manner?).
>>>>>>>>>
>>>>>>>>> > However, I usually use a DMPlex which knows about my
>>>>>>>>> > mesh, so I am not sure if this strategy has any holes.
>>>>>>>>>
>>>>>>>>> I haven't noticed anything yet.
>>>>>>>>>
>>>>>>>>> Lawrence
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> 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
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> 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
>>>>
>>>
>>>
>>
>>
>> --
>> 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
>>
>
>
>
> --
> 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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