[petsc-dev] FieldSplit with different nonzero pattern

[Hong]

Pierre:
I added this support
https://bitbucket.org/petsc/petsc/commits/ef7efd37182b12f7b7ab7c34390aae8e592a83c2

It is in branch hzhang/fix-pc-fieldsplit-reuse.
You may give it a try. Once it passed all our regression tests, it will be
merged to petsc-master branch.

Your modified ex42.c is very helpful, thanks!
Hong

On Fri, May 4, 2018 at 10:15 AM, Hong <hzhang at mcs.anl.gov> wrote:

> Pierre:
> Thanks for creating this use case. I'll check it and get back to you
> sometime next week.
> Hong
>
> Hong,
>> Thanks for your reply.
>> It’s not so minimalist, but at least it is based on one of your example.
>> diff --git a/src/ksp/ksp/examples/tutorials/ex42.c
>> b/src/ksp/ksp/examples/tutorials/ex42.c
>> index 8be4389a2d..520c82569a 100644
>> --- a/src/ksp/ksp/examples/tutorials/ex42.c
>> +++ b/src/ksp/ksp/examples/tutorials/ex42.c
>> @@ -1953,6 +1953,15 @@ static PetscErrorCode
>> solve_stokes_3d_coupled(PetscInt mx,PetscInt my,PetscInt m
>>      }
>>    }
>>    ierr = KSPSolve(ksp_S,f,X);CHKERRQ(ierr);
>> +  PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,
>> PETSC_VIEWER_ASCII_INFO);
>> +  MatView(A, PETSC_VIEWER_STDOUT_WORLD);
>> +  Mat C;
>> +  MatMatMult(A, A, MAT_INITIAL_MATRIX, PETSC_DEFAULT, &C);
>> +  MatView(C, PETSC_VIEWER_STDOUT_WORLD);
>> +  PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
>> +  ierr = KSPSetOperators(ksp_S,C,C);CHKERRQ(ierr);
>> +  ierr = KSPSolve(ksp_S,f,X);CHKERRQ(ierr);
>> +  MatDestroy(&C);
>>
>>    ierr = PetscOptionsGetBool(NULL,NULL,"-write_pvts",&write_output,NU
>> LL);CHKERRQ(ierr);
>>    if (write_output) {ierr = DAView3DPVTS(da_Stokes,X,"up")
>> ;CHKERRQ(ierr);}
>>
>> $ mpirun -np 1 ./ex42 -mx 2 -my 2 -mz 2 -stokes_pc_type fieldsplit
>> This should give you this exact error.
>> Do you know of a way to bypass the error by flushing/destroying the PC
>> while still keeping the options for the following KSPSolve?
>>
>> Thanks in advance,
>> Pierre
>>
>> On 3 May 2018, at 5:07 PM, Hong <hzhang at mcs.anl.gov> wrote:
>>
>> Pierre :
>> The code crashes inside
>> if (scall == MAT_REUSE_MATRIX) {
>> ...
>> }
>> which assumes both original matrix and its submatrices data structures
>> remain unchanged.
>> We did not anticipate the usage of looping
>>
>>>
>>> 3) change the sparsity pattern of the Mat for one of the field
>>> 4) do a KSPSolve
>>>
>>
>> Can you send us a stand-alone code for this type of application.
>> We will investigate how to support it.
>>
>> Hong
>>
>> I cannot change this calling sequence, because I’d like to nest 3) and 4)
>>> inside a loop.
>>> However, I end up with this error during 4):
>>> [0]PETSC ERROR: Nonconforming object sizes
>>> [0]PETSC ERROR: Cannot reuse matrix. wrong no of nonzeros
>>> [0]PETSC ERROR: Petsc Development GIT revision: v3.9-13-g05d412bc58  GIT
>>> Date: 2018-04-09 08:39:52 -0500
>>>
>>> [0]PETSC ERROR: #1 MatCreateSubMatrix_SeqAIJ() line 2330 in
>>> /Users/jolivet/Documents/repositories/petsc/src/mat/impls/aij/seq/aij.c
>>> [0]PETSC ERROR: #2 MatCreateSubMatrix_MPIAIJ_SameRowColDist() line 3184
>>> in /Users/jolivet/Documents/repositories/petsc/src/mat/impls/ai
>>> j/mpi/mpiaij.c
>>> [0]PETSC ERROR: #3 MatCreateSubMatrix_MPIAIJ() line 3310 in
>>> /Users/jolivet/Documents/repositories/petsc/src/mat/impls/ai
>>> j/mpi/mpiaij.c
>>> [0]PETSC ERROR: #4 MatCreateSubMatrix() line 7813 in
>>> /Users/jolivet/Documents/repositories/petsc/src/mat/interface/matrix.c
>>> [0]PETSC ERROR: #5 PCSetUp_FieldSplit() line 564 in
>>> /Users/jolivet/Documents/repositories/petsc/src/ksp/pc/impls
>>> /fieldsplit/fieldsplit.c
>>> [0]PETSC ERROR: #6 PCSetUp() line 923 in /Users/jolivet/Documents/repos
>>> itories/petsc/src/ksp/pc/interface/precon.c
>>> [0]PETSC ERROR: #7 PCApply() line 453 in /Users/jolivet/Documents/repos
>>> itories/petsc/src/ksp/pc/interface/precon.c
>>> [0]PETSC ERROR: #8 KSP_PCApply() line 276 in
>>> /Users/jolivet/repo/petsc/include/petsc/private/kspimpl.h
>>> [0]PETSC ERROR: #9 KSPFGMRESCycle() line 166 in
>>> /Users/jolivet/Documents/repositories/petsc/src/ksp/ksp/impl
>>> s/gmres/fgmres/fgmres.c
>>> [0]PETSC ERROR: #10 KSPSolve_FGMRES() line 291 in
>>> /Users/jolivet/Documents/repositories/petsc/src/ksp/ksp/impl
>>> s/gmres/fgmres/fgmres.c
>>> [0]PETSC ERROR: #11 KSPSolve() line 669 in /Users/jolivet/Documents/repos
>>> itories/petsc/src/ksp/ksp/interface/itfunc.c
>>>
>>> Is this the expected behaviour? Would you need a MWE?
>>> What I find funny is that if I turn -info on, then just before the
>>> error, I get:
>>> [0] PCSetUp(): Setting up PC with different nonzero pattern
>>> So why is it trying to reuse the matrix? I am missing a call to some
>>> function?
>>>
>>> Thanks in advance,
>>> Pierre
>>
>>
>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20180507/f2cbeea4/attachment.html>