[petsc-users] Converting a Parallel(MPI) Matrix to a Sequential Matrix

[Anthony Dowling]

But in theory, should I be able to get the rows or values from the
sequential matrix and insert them into a parallel matrix manually? I think
that would do what I need.

Thanks,
Anthony Dowling


On Mon, Sep 7, 2020 at 11:20 AM Matthew Knepley <knepley at gmail.com> wrote:

> On Mon, Sep 7, 2020 at 11:17 AM Anthony Dowling <dowlinah at clarkson.edu>
> wrote:
>
>> Thank you for your help, Matthew.
>>
>> With those methods, will I be able to copy the contents of the created
>> serial matrices back to a parallel matrix if needed? If so, what is a good
>> way to do that?
>>
>
> There is nothing that does that right now. We would have to write it.
>
>   Thanks,
>
>      Matt
>
>
>> Thanks,
>> Anthony Dowling
>>
>>
>> On Mon, Sep 7, 2020 at 11:12 AM Matthew Knepley <knepley at gmail.com>
>> wrote:
>>
>>> On Mon, Sep 7, 2020 at 11:00 AM Anthony Dowling <dowlinah at clarkson.edu>
>>> wrote:
>>>
>>>> Hello all,
>>>>
>>>> Is there a method to convert a parallel(MPI) dense matrix to a
>>>> sequential dense matrix? Also to do the same in reverse? The code I am
>>>> using needs to be able to convert a float** matrix to a Petsc matrix, and
>>>> then later convert that Petsc matrix between MPI dense and sequential
>>>> dense. How might this be achieved? The code seems to be converting float**
>>>> matrices to Petsc properly, but I am unable to find a method to convert
>>>> between MPI and sequential matrices.
>>>>
>>>
>>> If you want the serial matrix everywhere, this is easy:
>>> https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatCreateRedundantMatrix.html
>>> If you want it just on 1 process, you can use:
>>> https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatCreateSubMatrices.html
>>>
>>>   Thanks,
>>>
>>>     Matt
>>>
>>>
>>>> Thanks in advance,
>>>> Anthony Dowling
>>>>
>>>
>>>
>>> --
>>> 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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