[petsc-users] Matload with given parallel layout

[Matthew Knepley]

On Wed, Oct 25, 2017 at 6:10 AM, Karin&NiKo <niko.karin at gmail.com> wrote:

> Thank you very much for your answer.
> Is there an example in the PETSc tests that shows how to prescribe the
> layout of the Mat that is passed to MatLoad()? I see how to specify a local
> size with MatSetSize but I do not see how to assign an entry of the Mat to
> a given process...
>

Mat object only have contiguous division of rows on processes, so
specifying the size of each partition is all you can do.

   Matt


> Thanks,
> Nicolas
>
> 2017-10-25 11:40 GMT+02:00 Matthew Knepley <knepley at gmail.com>:
>
>> On Wed, Oct 25, 2017 at 4:32 AM, Karin&NiKo <niko.karin at gmail.com> wrote:
>>
>>> Dear PETSc team,
>>>
>>> I have a code that creates a parallel matrix based on domain
>>> decomposition. I serialize this matrix with MatView.
>>> Then, I would like to relaod it with MatLoad but not leaving PETSc
>>> decide the parallel layout but rather use the original distribution of the
>>> degrees of freedom.
>>> Does MatLoad help to do that? Shall  I use the IS of the local/global
>>> mapping ?
>>>
>>
>> You can prescribe the layout of the Mat that is passed to MatLoad().
>> However, if you are asking that the original
>> layout be stored in the file, we do not do that. It could be made to work
>> by writing the layout to the .info file and
>> then having the option call MatSetSizes() on load. Should not be much
>> code.
>>
>>   Thanks,
>>
>>      Matt
>>
>>
>>> I look forward to reading you,
>>> Nicolas
>>>
>>>
>>>
>>
>>
>> --
>> 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.caam.rice.edu/~mk51/>
>>
>
>


-- 
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.caam.rice.edu/~mk51/>
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