[petsc-users] On PCFIELDSPLIT and its implementation

[Edoardo alinovi]

Sure,

I'll try on a 3x3 cavity. How can I print the ISs?

Il Mer 9 Nov 2022, 14:07 Matthew Knepley <knepley at gmail.com> ha scritto:

> On Wed, Nov 9, 2022 at 7:57 AM Edoardo alinovi <edoardo.alinovi at gmail.com>
> wrote:
>
>> To be clear,
>>
>> You are suggesting to use ufields(0)=0, ufields(1)=1 and so on?
>>
>
> I think you are right. Those should start from 1. However, your ISes do
> not seem to cover
> the whole matrix. Can you start with a very small problem so that you can
> print them to
> the screen?
>
>   Thanks,
>
>      Matt
>
>
>> Il Mer 9 Nov 2022, 13:54 Edoardo alinovi <edoardo.alinovi at gmail.com> ha
>> scritto:
>>
>>> Even in the fortran interface?
>>>
>>> Il Mer 9 Nov 2022, 13:52 Matthew Knepley <knepley at gmail.com> ha scritto:
>>>
>>>> Fields are numbered from 0.
>>>>
>>>>   Thanks,
>>>>
>>>>      Matt
>>>>
>>>> On Wed, Nov 9, 2022 at 2:20 AM Edoardo alinovi <
>>>> edoardo.alinovi at gmail.com> wrote:
>>>>
>>>>> Hello guys,
>>>>>
>>>>> I am getting this error while using fieldsplit:
>>>>>
>>>>> [3]PETSC ERROR: --------------------- Error Message
>>>>> --------------------------------------------------------------
>>>>>
>>>>> *[3]PETSC ERROR: Nonconforming object sizes[3]PETSC ERROR: Local
>>>>> column sizes 6132 do not add up to total number of columns 9200*
>>>>> [3]PETSC ERROR: See https://petsc.org/release/faq/ for trouble
>>>>> shooting.
>>>>> [3]PETSC ERROR: Petsc Development GIT revision:
>>>>> v3.18.1-191-g32ed6ae2ff2  GIT Date: 2022-11-08 12:22:17 -0500
>>>>> [3]PETSC ERROR: flubio_coupled on a gnu named alienware by edo Wed Nov
>>>>>  9 08:16:29 2022
>>>>> [3]PETSC ERROR: Configure options PETSC_ARCH=gnu FOPTFLAGS=-O3
>>>>> COPTFLAGS=-O3 CXXOPTFLAGS=-O3 -with-debugging=no -download-fblaslapack=1
>>>>> -download-superlu_dist -download-mumps -download-hypre -download-metis
>>>>> -download-parmetis -download-scalapack -download-ml -download-slepc
>>>>> -download-hpddm -download-cmake
>>>>> -with-mpi-dir=/home/edo/software/openmpi-4.1.1/build/
>>>>> [3]PETSC ERROR: #1 MatCreateSubMatrix_MPIBAIJ_Private() at
>>>>> /home/edo/software/petsc/src/mat/impls/baij/mpi/mpibaij.c:1987
>>>>> [3]PETSC ERROR: #2 MatCreateSubMatrix_MPIBAIJ() at
>>>>> /home/edo/software/petsc/src/mat/impls/baij/mpi/mpibaij.c:1911
>>>>> [3]PETSC ERROR: #3 MatCreateSubMatrix() at
>>>>> /home/edo/software/petsc/src/mat/interface/matrix.c:8340
>>>>> [3]PETSC ERROR: #4 PCSetUp_FieldSplit() at
>>>>> /home/edo/software/petsc/src/ksp/pc/impls/fieldsplit/fieldsplit.c:657
>>>>> [3]PETSC ERROR: #5 PCSetUp() at
>>>>> /home/edo/software/petsc/src/ksp/pc/interface/precon.c:994
>>>>> [3]PETSC ERROR: #6 KSPSetUp() at
>>>>> /home/edo/software/petsc/src/ksp/ksp/interface/itfunc.c:406
>>>>> [3]PETSC ERROR: #7 KSPSolve_Private() at
>>>>> /home/edo/software/petsc/src/ksp/ksp/interface/itfunc.c:825
>>>>> [3]PETSC ERROR: #8 KSPSolve() at
>>>>> /home/edo/software/petsc/src/ksp/ksp/interface/itfunc.c:1071
>>>>>
>>>>> Do you have any ideas? Probably something missing in my brief
>>>>> implementation here:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> *            call PCSetType(mypc, PCFIELDSPLIT, ierr)
>>>>> call PCFieldSplitSetBlockSize(mypc, 4-bdim, ierr)           *
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> *            !2D, 3x3 block            if(bdim==1) then
>>>>>   ufields(1) = 0                ufields(2) = 1                pfields(1) =
>>>>> 2                call PCFieldSplitSetFields(mypc, "u", 2, ufields, ufields,
>>>>> ierr)                call PCFieldSplitSetFields(mypc, "p", 1, pfields,
>>>>> pfields, ierr)             ! 3D 4x4 block            else
>>>>> ufields(1) = 0                ufields(2) = 1                ufields(3) = 2
>>>>>               pfields(1) = 3                call
>>>>> PCFieldSplitSetFields(mypc, "u", 3, ufields, ufields, ierr)
>>>>> call PCFieldSplitSetFields(mypc, "p", 1, pfields, pfields, ierr)
>>>>> endif                         ! Field split type ADDITIVE, MULTIPLICATIVE
>>>>> (default), SYMMETRIC_MULTIPLICATIVE, SPECIAL, SCHUR            call
>>>>> PCFieldSplitSetType(mypc, PC_COMPOSITE_SCHUR, ierr)*
>>>>>
>>>>> Thanks for the help!
>>>>>
>>>>
>>>>
>>>> --
>>>> 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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