[petsc-users] PCFactorSetMatOrderingType not working with 3.21

[Zou, Ling]

Barry, thanks.
I am accessing PETSc through MOOSE. I need to figure out if the versions are consistent and how to test it.
-Ling

From: Barry Smith <bsmith at petsc.dev>
Date: Saturday, August 17, 2024 at 12:08 PM
To: Zou, Ling <lzou at anl.gov>
Cc: petsc-users at mcs.anl.gov <petsc-users at mcs.anl.gov>
Subject: Re: [petsc-users] PCFactorSetMatOrderingType not working with 3.21
I have attached src/snes/tutorials/ex5. c in which I tried to reproduce your problem by inserting the code you've indicated. However I am not getting the problem you see, I am seeing, type: ilu out-of-place factorization 0 levels of fill tolerance
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   I have attached src/snes/tutorials/ex5.c in which I tried to reproduce your problem by inserting the code you've indicated.

   However I am not getting the problem you see, I am seeing,


    type: ilu

      out-of-place factorization

      0 levels of fill

      tolerance for zero pivot 2.22045e-14

      matrix ordering: rcm


when I run with -pc_type ilu -snes_view

 Can you please confirm you get the same problem with the attached ex5.c ?  You could send your code to see if I can reproduce the problem.

  I am using the release branch of PETSc

  Barry









On Aug 17, 2024, at 12:35 PM, Zou, Ling via petsc-users <petsc-users at mcs.anl.gov> wrote:

Hi all,

The following codes are how I used to setup PC mat ordering:

  // Setup KSP/PC (at this moment, user-input options and commandline options are available)
  SNESGetKSP(snes, &ksp);
  KSPSetFromOptions(ksp);
  PC pc;
  KSPGetPC(ksp, &pc);
  PCFactorSetMatOrderingType(pc, MATORDERINGRCM);
  // PCFactorSetLevels(pc, 5);
  SNESSetFromOptions(snes);

After switching to PETSc 3.21, this no longer works, and can be confirmed from ‘-snes_view’ output:

  PC Object: 1 MPI process
    type: ilu
      out-of-place factorization
      0 levels of fill
      tolerance for zero pivot 2.22045e-14
      using diagonal shift to prevent zero pivot [NONZERO]
      matrix ordering: natural

The command line option still works, i.e., ‘-pc_factor_mat_ordering_type rcm’ gives me the correct behavior.

Questions:

  *   Is this a bug introduced in the new version, or
  *   With the new version, I should call this function at a different time?

Best,

-Ling

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