[petsc-users] parallel computing error

[Barry Smith]

  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 <mailto:knepley at gmail.com>>님이 작성:
>> On Wed, May 3, 2023 at 6:05 AM ­권승리 / 학생 / 항공우주공학과 <ksl7912 at snu.ac.kr <mailto: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 <mailto: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 <mailto:ksl7912 at snu.ac.kr>
> Office : +82-2-880-7389
> C. P : +82-10-4695-1062

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