[petsc-users] IS natural numbering to global numbering

[Matthew Knepley]

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/>
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