[petsc-users] parallel computing error

[­권승리 / 학생 / 항공우주공학과]

Dear Barry Smith

Thank you for your reply.

I've already installed MUMPS.

And I checked the example you said (ex125.c), I don't understand why the
RHS matrix becomes the SeqDense matrix.

Could you explain in more detail?

Best regards
Seung Lee Kwon

2023년 5월 4일 (목) 오후 12:08, Barry Smith <bsmith at petsc.dev>님이 작성:

>
>   You can configure with MUMPS ./configure --download-mumps
> --download-scalapack --download-ptscotch --download-metis
> --download-parmetis
>
>   And then use MatMatSolve() as in src/mat/tests/ex125.c with parallel
> MatMatSolve() using MUMPS as the solver.
>
>   Barry
>
>
> On May 3, 2023, at 10:29 PM, ­권승리 / 학생 / 항공우주공학과 <ksl7912 at snu.ac.kr>
> wrote:
>
> Dear developers
>
> Thank you for your explanation.
>
> But I should use the MatCreateSeqDense because I want to use the
> MatMatSolve that B matrix must be a SeqDense matrix.
>
> Using MatMatSolve is an inevitable part of my code.
>
> Could you give me a comment to avoid this error?
>
> Best,
>
> Seung Lee Kwon
>
> 2023년 5월 3일 (수) 오후 7:30, Matthew Knepley <knepley at gmail.com>님이 작성:
>
>> On Wed, May 3, 2023 at 6:05 AM ­권승리 / 학생 / 항공우주공학과 <ksl7912 at snu.ac.kr>
>> wrote:
>>
>>> Dear developers
>>>
>>> I'm trying to use parallel computing and I ran the command 'mpirun -np 4
>>> ./app'
>>>
>>> In this case, there are two problems.
>>>
>>> *First,* I encountered error message
>>> ///
>>> [0]PETSC ERROR: [1]PETSC ERROR: --------------------- Error Message
>>> --------------------------------------------------------------
>>> [1]PETSC ERROR: Invalid argument
>>> [1]PETSC ERROR: Comm must be of size 1
>>> ///
>>> The code on the error position is
>>> MatCreateSeqDense(PETSC_COMM_SELF, nns, ns, NULL, &Kns));
>>>
>>
>> 1) "Seq" means sequential, that is "not parallel".
>>
>> 2) This line should still be fine since PETSC_COMM_SELF is a serial
>> communicator
>>
>> 3) You should be checking the error code for each call, maybe using the
>> CHKERRQ() macro
>>
>> 4) Please always send the entire error message, not a snippet
>>
>>   THanks
>>
>>      Matt
>>
>>
>>> Could "MatCreateSeqDense" not be used in parallel computing?
>>>
>>> *Second*, the same error message is repeated as many times as the
>>> number of cores.
>>> if I use command -np 4, then the error message is repeated 4 times.
>>> Could you recommend some advice related to this?
>>>
>>> Best,
>>> Seung Lee Kwon
>>>
>>> --
>>> Seung Lee Kwon, Ph.D.Candidate
>>> Aerospace Structures and Materials Laboratory
>>> Department of Mechanical and Aerospace Engineering
>>> Seoul National University
>>> Building 300 Rm 503, Gwanak-ro 1, Gwanak-gu, Seoul, South Korea, 08826
>>> E-mail : ksl7912 at snu.ac.kr
>>> Office : +82-2-880-7389
>>> C. P : +82-10-4695-1062
>>>
>>
>>
>> --
>> 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/>
>>
>
>
> --
> Seung Lee Kwon, Ph.D.Candidate
> Aerospace Structures and Materials Laboratory
> Department of Mechanical and Aerospace Engineering
> Seoul National University
> Building 300 Rm 503, Gwanak-ro 1, Gwanak-gu, Seoul, South Korea, 08826
> E-mail : ksl7912 at snu.ac.kr
> Office : +82-2-880-7389
> C. P : +82-10-4695-1062
>
>
>

-- 
Seung Lee Kwon, Ph.D.Candidate
Aerospace Structures and Materials Laboratory
Department of Mechanical and Aerospace Engineering
Seoul National University
Building 300 Rm 503, Gwanak-ro 1, Gwanak-gu, Seoul, South Korea, 08826
E-mail : ksl7912 at snu.ac.kr
Office : +82-2-880-7389
C. P : +82-10-4695-1062
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