[petsc-users] how to output components of a section

[Matthew Knepley]

On Wed, Nov 9, 2016 at 11:54 PM, leejearl <leejearl at 126.com> wrote:

> Hi, Matt
>     Thanks for your reply, and will it be solved in the newest version of
> PETSc?
>

Yes, we are just working out how to do it. I might not actually code it
until classes end Dec. 2. Is that
an okay timeline?

  Thanks,

     Matt


>
> leejearl
>
>
> On 2016年11月07日 20:09, Matthew Knepley wrote:
>
> On Mon, Nov 7, 2016 at 4:17 AM, Sander Arens <Sander.Arens at ugent.be>
> wrote:
>
>> Ok, I see what happened.
>> If you create a a vector with DMGetGlobalVector, the VecView function is
>> overloaded with some DM-specific VecView function (e.g. VecView_Plex), but
>> this doesn't happen with the vec that you get from VecGetSubVector. So one
>> way to solve this would be to create a global vector from your subdm and do
>> the scatters yourself.
>> But I think it would be better if these VecView operations could be
>> copied from the original vec in VecGetSubVector?
>>
>
> You are right. I am moving this to petsc-dev temporarily for discussion.
>
>   Thanks,
>
>     Matt
>
>
>> Thanks,
>> Sander
>>
>> On 7 November 2016 at 09:08, leejearl <leejearl at 126.com> wrote:
>>
>>> Hi Sander:
>>>     Thank your for your assistance, but it is still not works. The code
>>> is now as follows:
>>>         Vec subX, X;
>>>         DM subdm;
>>>         IS subIS;
>>>         PetscInt numSubFields = 2;
>>>         PetscInt subFields[2];
>>>         subFields[0] = 0; subFields[1] =1 ;
>>>         ierr = DMCreateSubDM(dm, numSubFields, subFields, &subIS,
>>> &subdm);CHKERRQ(ierr);
>>>         ierr = DMGetGlobalVector(dm, &X);CHKERRQ(ierr);
>>>         ierr = VecGetSubVector(X,subIS,&subX);CHKERRQ(ierr);
>>>         ierr = VecSetDM(subX, dm);CHKERRQ(ierr);
>>>
>>>>         ierr = PetscObjectSetName((PetscObject) subX,
>>>> "sol.");CHKERRQ(ierr);
>>>>         ierr = PetscViewerSetType(*viewer,
>>>> PETSCVIEWERVTK);CHKERRQ(ierr);
>>>>        ierr = PetscViewerPushFormat(*viewer,
>>>> PETSC_VIEWER_VTK_VTU);CHKERRQ(ierr);
>>>>         ierr = PetscViewerFileSetName(*viewer,
>>>> "subsol.vtu");CHKERRQ(ierr);
>>>>         ierr = VecView(subX, viewer);CHKERRQ(ierr);
>>>>         ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
>>>>         ierr = VecRestoreSubVector(X, subIS, &subX);CHKERRQ(ierr);
>>>>         DMDestroy(&subdm);
>>>>         ierr = DMRestoreGlobalVector(dm, &X);CHKERRQ(ierr);
>>>>
>>>
>>>
>>> I have add "VecSetDm", but it has not output file.
>>>
>>> Thanks
>>> leejearl
>>>
>>> On 2016年11月07日 15:35, Sander Arens wrote:
>>>
>>> Does it work if you put
>>> ierr = VecSetDM(subX, subdm);CHKERRQ(ierr);
>>> before the VecView?
>>>
>>> Thanks,
>>> Sander
>>>
>>> On 7 November 2016 at 03:50, leejearl <leejearl at 126.com> wrote:
>>>
>>>> Hi, Barry:
>>>>     I must have some make some mistakes. I post the code as follows:
>>>>         Vec subX, X;
>>>>         DM subdm;
>>>>         IS subIS;
>>>>         PetscInt numSubFields = 2;
>>>>         PetscInt subFields[2];
>>>>         subFields[0] = 0; subFields[1] =1 ;
>>>>         ierr = DMCreateSubDM(dm, numSubFields, subFields, &subIS,
>>>> &subdm);CHKERRQ(ierr);
>>>>         ierr = DMGetGlobalVector(dm, &X);CHKERRQ(ierr);
>>>>         ierr = VecGetSubVector(X,subIS,&subX);CHKERRQ(ierr);
>>>>         ierr = PetscObjectSetName((PetscObject) subX,
>>>> "sol.");CHKERRQ(ierr);
>>>>         ierr = PetscViewerSetType(*viewer,
>>>> PETSCVIEWERVTK);CHKERRQ(ierr);
>>>>        ierr = PetscViewerPushFormat(*viewer,
>>>> PETSC_VIEWER_VTK_VTU);CHKERRQ(ierr);
>>>>         ierr = PetscViewerFileSetName(*viewer,
>>>> "subsol.vtu");CHKERRQ(ierr);
>>>>         ierr = VecView(subX, viewer);CHKERRQ(ierr);
>>>>         ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
>>>>         ierr = VecRestoreSubVector(X, subIS, &subX);CHKERRQ(ierr);
>>>>         DMDestroy(&subdm);
>>>>         ierr = DMRestoreGlobalVector(dm, &X);CHKERRQ(ierr);
>>>>
>>>> There are three fields in dm, and I want to obtain the vector of the
>>>> two of them. But, I can not
>>>> get the output file “subsol.vtu”. Can you help me with the code?
>>>>
>>>> Thanks
>>>> leejearl
>>>>
>>>> On 2016年11月06日 12:21, Barry Smith wrote:
>>>>
>>>>> On Nov 5, 2016, at 8:36 PM, leejearl <leejearl at 126.com> wrote:
>>>>>>
>>>>>> Hi Sander:
>>>>>>      Thank you for your advices, and it works. But it is only
>>>>>> available in th local vector.
>>>>>>
>>>>>    This should work on the global vector. Please send the full output
>>>>> of the error messages when used with a global vector.
>>>>>
>>>>>     Barry
>>>>>
>>>>> Is there any methods to reach this purposes in the global vector?
>>>>>>      Thanks
>>>>>> leejearl
>>>>>> On 2016年11月05日 19:29, Sander Arens wrote:
>>>>>>
>>>>>>> You can first obtain an IS with
>>>>>>> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/
>>>>>>> DM/DMCreateSubDM.html
>>>>>>> and with that you can obtain a subvector with
>>>>>>> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/
>>>>>>> Vec/VecGetSubVector.html
>>>>>>> which you can then view the usual way.
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Sander
>>>>>>>
>>>>>>> On 5 November 2016 at 12:17, leejearl <leejearl at 126.com> wrote:
>>>>>>> Hi, all:
>>>>>>>
>>>>>>>      I meet a problems which I can not overcome. The programe is
>>>>>>> like the code in
>>>>>>>
>>>>>>> "http://www.mcs.anl.gov/petsc/petsc-current/src/dm/impls/ple
>>>>>>> x/examples/tutorials/ex1.c.html".
>>>>>>>
>>>>>>>     The code create a section which has three fields: u,v,w. How can
>>>>>>> I output the fields u and v without together with w?
>>>>>>>
>>>>>>>     Thanks!
>>>>>>>
>>>>>>>
>>>>>>> leejearl
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>
>>>>
>>>
>>>
>>
>
>
> --
> 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
>
>
> --
> 李季
> 西北工业大学航空学院流体力学系
> Phone: 17792092487
> QQ: 188524324
>
>


-- 
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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