[petsc-users] petscviewerduplicate?

[Nachiket Gokhale]

On Wed, Mar 20, 2013 at 4:22 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>   Why not just use one file, if Matlab is going to read them, it saves you typing both when saving the matrices and when reading them in Matlab?

Because I didn't realize I could store multiple matrices in one file.
Is this true for binary as well?

>
>   If the matrices are not tiny you likely also want to use the binary viewer, it will be much faster and work in parallel.

I am using the binary viewer. Matlab is there for debugging.

-Nachiket

>
>    Barry
>
> On Mar 20, 2013, at 1:28 PM, Nachiket Gokhale <gokhalen at gmail.com> wrote:
>
>> I have this in my code:
>>
>> ierr = PetscViewerCreate(PETSC_COMM_WORLD,&RightViewer);CHKERRQ(ierr);
>> ierr = PetscViewerSetType(RightViewer,PETSCVIEWERASCII);CHKERRQ(ierr);
>> ierr = PetscViewerFileSetMode(RightViewer,FILE_MODE_WRITE);CHKERRQ(ierr);
>> ierr = PetscViewerSetFormat(RightViewer,PETSC_VIEWER_ASCII_MATLAB);CHKERRQ(ierr);
>>
>> ierr = PetscViewerCreate(PETSC_COMM_WORLD,&LeftViewer);CHKERRQ(ierr);
>> ierr = PetscViewerSetType(LeftViewer,PETSCVIEWERASCII);CHKERRQ(ierr);
>> ierr = PetscViewerFileSetMode(LeftViewer,FILE_MODE_WRITE);CHKERRQ(ierr);
>> ierr = PetscViewerSetFormat(LeftViewer,PETSC_VIEWER_ASCII_MATLAB);CHKERRQ(ierr);
>>
>> It would have been nice to create the LeftViewer from the RightViewer.
>> That is what I am trying to do.
>>
>> At other places I use only one viewer to output left and right matrices:
>>
>> // projection matrices in ascii
>>  ierr = PetscViewerCreate(PETSC_COMM_WORLD,&ProjMatViewer);CHKERRQ(ierr);
>>  ierr = PetscViewerSetType(ProjMatViewer,PETSCVIEWERASCII);CHKERRQ(ierr);
>>  ierr = PetscViewerFileSetMode(ProjMatViewer,FILE_MODE_WRITE);CHKERRQ(ierr);
>>  ierr = PetscViewerSetFormat(ProjMatViewer,PETSC_VIEWER_ASCII_MATLAB);CHKERRQ(ierr);
>>  // right
>>  ierr = PetscViewerFileSetName(ProjMatViewer,projfileasciiright);CHKERRQ(ierr);
>>  ierr = MatView(ProjMatRight,ProjMatViewer);CHKERRQ(ierr);
>>  // left
>>  ierr = PetscViewerFileSetName(ProjMatViewer,projfileasciileft);CHKERRQ(ierr);
>>  ierr = MatView(ProjMatLeft,ProjMatViewer);CHKERRQ(ierr);
>>  // destroy
>>  ierr = PetscViewerDestroy(&ProjMatViewer);CHKERRQ(ierr);
>>
>> But I think switching the filename is inconvenient - I'd rather create
>> a separate viewer Left and Right Matrices and have it copy the same
>> parameters from an already created viewer.
>>
>> -Nachiket
>>
>> On Wed, Mar 20, 2013 at 2:16 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
>>> What would it mean to duplicate a viewer? What are you actually trying to
>>> do?
>>>
>>> On Mar 20, 2013 12:59 PM, "Nachiket Gokhale" <gokhalen at gmail.com> wrote:
>>>>
>>>> Not a show stopper, but would it be possible to add a
>>>> PetscViewerDuplicate function? I don't see such a function here -
>>>>
>>>> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Viewer/index.html
>>>>
>>>> Cheers, -Nachiket
>