[petsc-users] GlobalToLocal between DM and SubDM

[Josh L]

Thank you.
I just have a coupled problem, and i want to solve it beginning with
stagger then couple.



Matthew Knepley <knepley at gmail.com> 於 2019年4月30日 週二 下午12:57寫道：

> On Tue, Apr 30, 2019 at 1:20 PM Josh L via petsc-users <
> petsc-users at mcs.anl.gov> wrote:
>
>> Hi,
>>
>> I have a DM that that has 2 sections:
>>
>> section_0 has 2 dofs: u, v
>> section_1 has 1 dofs: p
>>
>> and a SubDM created by DMCreateSubDM. SubDM only has section_1.
>>
>> There are a global vector created with DM, and a local vector created
>> with SubDM
>>
>> Can I do GlobalToLocal between this 2 vectors?
>>
>
> No, the global and local vector have to have the same DM.
>
> If yes, which DM should I use when calling GlobalToLocal.
>>
>> Basically, I want
>> a global vec: [u1, v1, p1 u2, v2, p2, u3, v3, p3......]
>> to
>> local vec: [all dof p that belongs to this processor]
>>
>
> You will have to do it in two steps, either,
>
>   1) Extract p in a subDM, and then do G2L on that
>
> or
>
>   2) Do G2L on the full DM, and then extract p from the local vec
>
> 1) sounds better to me, but I do not know what your code is doing.
>
>   Thanks,
>
>     Matt
>
>
>>
>> Thanks,
>> Yu-Sheng
>>
>>
>>
>>
>>
>>
>
> --
> 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/20190430/5aac3fa6/attachment.html>