[petsc-users] Difference between DMGetLocalVector and DMCreateLocalVector

[Matthew Knepley]

You are right. I was not clearing the caches when the section was reset.
Stefano ahs fixed this now:

  https://urldefense.us/v3/__https://gitlab.com/petsc/petsc/-/merge_requests/7314__;!!G_uCfscf7eWS!ZPkq_k9vdzTZxeW53aWVTIcDgeGnywSm0tGKDJkJqdwgTomfYjw1lsTMyRtAjtruSslcgLIoKGg7IILlBxbJ$ 

  Thanks,

     Matt

On Thu, Feb 22, 2024 at 4:24 AM Stefano Zampini <stefano.zampini at gmail.com>
wrote:

> I guess we are missing to clear the internal scratch vectors, matt can
> confirm
>
> Can you please add this call AFTER you set the local section to confirm?
>
>   call DMClearLocalVectors(dm_mesh, ierr);
>
>
> Il giorno gio 22 feb 2024 alle ore 11:36 袁煕 <yuanxi at advancesoft.jp> ha
> scritto:
>
>> Hello, I found DMGetLocalVector and DMCreateLocalVector generate Vec of
>> different size in my following codes ==================== call
>> PetscSectionSetup(section,ierr) call
>> DMSetLocalSection(dm_mesh,section,ierr) .. . . . . do somethingcall
>> PetscSectionSetup(section,ierr)call
>> ZjQcmQRYFpfptBannerStart
>> This Message Is From an External Sender
>> This message came from outside your organization.
>>
>> ZjQcmQRYFpfptBannerEnd
>>  Hello,
>>
>> I found DMGetLocalVector and DMCreateLocalVector generate Vec of
>> different size in my following codes
>>
>> ====================
>> call PetscSectionSetup(section,ierr)
>> call DMSetLocalSection(dm_mesh,section,ierr)
>> ......do something
>>
>> call PetscSectionSetup(section,ierr)
>> call DMSetLocalSection(dm_mesh,section,ierr)
>> ......
>> call DMCreateLocalVector(dm_mesh,lvec,ierr);
>> call DMGetLocalVector(dm_mesh,llvec,ierr);
>> call VecGetSize(lvec,off,ierr)
>> call VecGetSize(llvec,offl,ierr)
>> call VecDestroy(lvec,ierr)
>> call DMRestoreLocalVector(dm_mesh,llvec,ierr);
>> ========================
>> The pointer in the above program is that DMSetLocalSection is called two
>> times. As the petsc manual indicates, "Any existing Section will be
>> destroyed" after calling this function and To my understanding, a new
>> section should be set. Therefore,  The above program should obtain
>> values of *off* and *offl *the same. However, I found that they are
>> different, with *off *equal to the size defined by the new section and
>> *offl* equal to the size defined by the first one.
>>
>> Any problem in above codes? And how can I obtain a Vector of the same
>> size by DMGetLocalVector and DMCreateLocalVector?
>>
>> Much thanks for your help.
>>
>> X. Yuan, Ph.D. in Solid Mechanics
>>
>
>
> --
> Stefano
>


-- 
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://urldefense.us/v3/__https://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!ZPkq_k9vdzTZxeW53aWVTIcDgeGnywSm0tGKDJkJqdwgTomfYjw1lsTMyRtAjtruSslcgLIoKGg7IIE6dMV7$  <https://urldefense.us/v3/__http://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!ZPkq_k9vdzTZxeW53aWVTIcDgeGnywSm0tGKDJkJqdwgTomfYjw1lsTMyRtAjtruSslcgLIoKGg7IH_eS1w6$ >
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20240222/8d8190a8/attachment.html>