[petsc-users] IS natural numbering to global numbering

[Matthew Knepley]

On Sun, Jun 18, 2023 at 2:12 AM YuSh Lo <ysjosh.lo at gmail.com> wrote:

> I am getting a null PetscSF after calling DMPlexGetGlobalToNatural
>

Did you call DMDIstribute()? This is where the map is created because until
then, the map is identity.

  Thanks,

     Matt


> YuSh Lo <ysjosh.lo at gmail.com> 於 2023年6月18日 週日 上午12:18寫道：
>
>> Hi Matthew,
>>
>> After setting DMSetUseNatural to true and calling
>> DMPlexGetGlobalToNatural,
>> I call PestcSFView right away, it gives segmentation fault.
>> I have also tried DMGetNaturalSF, it also gives segmentation fault when
>> calling PetscSFView.
>> I use PETSC_VIEWER_STDOUT_WORLD as PetscViewer
>>
>> Thanks,
>> Josh
>>
>>
>> Matthew Knepley <knepley at gmail.com> 於 2023年6月9日 週五 下午1:04寫道：
>>
>>> On Fri, Jun 9, 2023 at 1:46 PM YuSh Lo <ysjosh.lo at gmail.com> wrote:
>>>
>>>> Hi Barry,
>>>>
>>>> Is there any way to use the mapping generated by DMPlexDistribute along
>>>> with AO?
>>>>
>>>
>>> For Plex, if you turn on
>>>
>>>   https://petsc.org/main/manualpages/DM/DMSetUseNatural/
>>>
>>> before DMPlexDistribute(), it will compute and store a GlobalToNatural
>>> map. This can be
>>> used to map vectors back and forth, but you can extract the SF
>>>
>>>   DMPlexGetGlobalToNaturalSF
>>> <https://petsc.org/main/manualpages/DMPlex/DMPlexGetGlobalToNaturalSF/>
>>>
>>> and use that to remap your IS, by extracting the indices.
>>>
>>>   THanks,
>>>
>>>      Matt
>>>
>>>
>>>> Thanks,
>>>> Josh
>>>>
>>>>
>>>> Barry Smith <bsmith at petsc.dev> 於 2023年6月9日 週五 上午10:42寫道：
>>>>
>>>>>
>>>>>   You might be looking for
>>>>> https://petsc.org/release/manualpages/AO/AO/#ao
>>>>>
>>>>>
>>>>> On Jun 9, 2023, at 11:02 AM, Mark Adams <mfadams at lbl.gov> wrote:
>>>>>
>>>>> An IS is just an array of integers. We need your context.
>>>>> Is this question for sparse matrices? If so look at the documentation
>>>>> on the AIJ matrix construction and the global vertex numbering system.
>>>>>
>>>>> Mark
>>>>>
>>>>> On Thu, Jun 8, 2023 at 1:15 PM YuSh Lo <ysjosh.lo at gmail.com> wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> I have an IS that contains some vertex that is in natural numbering.
>>>>>> How do I map them to global numbering without being distributed?
>>>>>>
>>>>>> Thanks,
>>>>>> Josh
>>>>>>
>>>>>
>>>>>
>>>
>>> --
>>> 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/>
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