[petsc-users] Finding nonzero indices

[Eda Oktay]

>
> Thank you for your answer Matt, but I have some questions about
> PetscBinaryWrite() since I am a new user.
>
> Since I am going to use this function, I guess I have to open a new binary
> file with PetscViewerBinaryOpen
> <https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Viewer/PetscViewerBinaryOpen.html#PetscViewerBinaryOpen>
>  and  PetscViewerBinaryGetDescriptor
> <https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Viewer/PetscViewerBinaryGetDescriptor.html#PetscViewerBinaryGetDescriptor>,
> and destroy viewer by  PetscViewerDestroy
> <https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Viewer/PetscViewerDestroy.html#PetscViewerDestroy>.
> Do I write these functions into for loop or not?
>
> Eda
>
> Matthew Knepley <knepley at gmail.com>, 25 Şub 2019 Pzt, 17:31 tarihinde
> şunu yazdı:
>
>> On Mon, Feb 25, 2019 at 5:25 AM Eda Oktay via petsc-users <
>> petsc-users at mcs.anl.gov> wrote:
>>
>>> Hello,
>>>
>>> I am trying to find the indices (both row and column separately) of
>>> nonzero entries of a sparse matrix in Petsc Binary Format. I found
>>> MatGetSeqNonzeroStructure but it gives me a struct and I don't know whether
>>> this is what I want or not.
>>>
>>
>> I would not do it that way, since it is fragile. I would write a loop
>> like this:
>>
>> MAtGetOwnershipRange();
>> for (row = rStart; row < rEnd; ++row) {
>>   MatGetRow()
>>   PetscBinaryWrite()
>>   MatRestoreRow()
>> }
>>
>> This will work for any matrix.
>>
>>     Matt
>>
>>
>>> Best regards,
>>>
>>> Eda
>>>
>>
>>
>> --
>> 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/20190225/31f846c9/attachment.html>