[petsc-users] Serial solution of system in MPI FEM application

[Matthew Knepley]

On Mon, Apr 19, 2021 at 9:04 AM Ivano Barletta <ivano.barletta at cmcc.it>
wrote:

> Thanks
>
> I've tried the first option, I get this compilation error
>
> undefined reference to `matcreatesubmatrices_'
>
> My PETSc version is 3.7.5, is this a feature of newer versions?
>

It was renamed from MatGetSubMatrix()

  https://www.mcs.anl.gov/petsc/documentation/changes/38.html

  Thanks,

     Matt


> Ivano
>
> Il giorno ven 16 apr 2021 alle ore 16:06 Matthew Knepley <
> knepley at gmail.com> ha scritto:
>
>> On Fri, Apr 16, 2021 at 9:46 AM Ivano Barletta <ivano.barletta at cmcc.it>
>> wrote:
>>
>>> Dear all,
>>>
>>> I have an MPI FEM application with an elliptic problem that I
>>> solve with PETSc. For debugging purposes I want to
>>> let the master process to solve the global system.
>>>
>>> Is there any simple way in PETSc to gather the distributed matrix
>>> (the type is MATMPIAIJ) on a single MPI process?
>>>
>>
>> You could use
>>
>>
>> https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatCreateSubMatrices.html
>>
>> to extract a single, serial matrix on process 0. However, you can do this
>> with the solver automatically using
>>
>>
>> https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PC/PCTELESCOPE.html
>>
>> If you have the memory, you can do this more simply with
>>
>>
>> https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PC/PCREDUNDANT.html
>>
>>   Thanks,
>>
>>      Matt
>>
>>
>>> Thanks,
>>> Ivano
>>>
>>>
>>>
>>
>> --
>> 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/>
>>
>

-- 
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/>
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