[petsc-users] PCFIELDSPLIT question

Tue Feb 2 15:01:23 CST 2016

Thanks again Matt. Unfortunately got the same errors with '0'. I think
both are valid in Fortran.

Hom Nath

On Tue, Feb 2, 2016 at 3:42 PM, Matthew Knepley <knepley at gmail.com> wrote:
> On Tue, Feb 2, 2016 at 2:35 PM, Hom Nath Gharti <hng.email at gmail.com> wrote:
>>
>> Thank you so much Matt.
>>
>> I now tried the following:
>>
>> ======================================================
>> call KSPCreate(PETSC_COMM_WORLD,ksp,ierr)
>> call KSPGetPC(ksp,pc,ierr)
>>
>> call PCFieldSplitSetIS(pc,"0",gdofu_is,ierr);
>> call ISDestroy(gdofu_is,ierr)
>> call PCFieldSplitSetIS(pc,"1",gdofchi_is,ierr);
>> call ISDestroy(gdofchi_is,ierr)
>> call PCFieldSplitSetIS(pc,"2",gdofp_is,ierr);
>> call ISDestroy(gdofp_is,ierr)
>> call PCFieldSplitSetIS(pc,"3",gdofphi_is,ierr);
>> call ISDestroy(gdofphi_is,ierr)
>>
>> ! Amat changes in each time steps
>> call KSPSetOperators(ksp,Amat,Amat,ierr) !version >= 3.5.0
>>
>> call KSPSolve(ksp,bvec,xvec,ierr)
>> ======================================================
>
>
> I am guessing that "0" is not a valid string for your Fortran compiler. Are
> you sure
> its not single quotes '0'?
>
>   Matt
>
>>
>> But I get the following error:
>>
>> [0]PETSC ERROR: --------------------- Error Message
>> --------------------------------------------------------------
>> [0]PETSC ERROR: Petsc has generated inconsistent data
>> [0]PETSC ERROR: Unhandled case, must have at least two fields, not 1
>> [0]PETSC ERROR: See
>> http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble
>> shooting.
>> [0]PETSC ERROR: Petsc Release Version 3.6.3, Dec, 03, 2015
>> [0]PETSC ERROR:
>> /tigress/hgharti/gitwork/SPECFEM3D_GLOBEVSPP/./bin/xspecfem3D on a
>> arch-linux2-c-debug named tiger-r3c1n7 by hgharti Tue Feb  2 15:
>> 29:30 2016
>> [0]PETSC ERROR: Configure options
>> --with-blas-lapack-dir=/opt/intel/composer_xe_2015.2.164/mkl/lib/intel64/
>> --with-cc=mpicc --with-cxx=mpicxx --wit
>> h-fc=mpif90 --with-mpiexec=mpiexec --with-debugging=1
>> --download-scalapack --download-mumps --download-pastix
>> --download-superlu --download-superlu_dist --download-metis
>> --download-parmetis --download-ptscotch --download-hypre
>> [0]PETSC ERROR: #1 PCFieldSplitSetDefaults() line 469 in
>>
>> /home/hgharti/lsoft/petsc-3.6.3-intel16-mpi5/src/ksp/pc/impls/fieldsplit/fieldsplit.c
>> [0]PETSC ERROR: #2 PCSetUp_FieldSplit() line 486 in
>>
>> /home/hgharti/lsoft/petsc-3.6.3-intel16-mpi5/src/ksp/pc/impls/fieldsplit/fieldsplit.c
>> [0]PETSC ERROR: #3 PCSetUp() line 983 in
>> /home/hgharti/lsoft/petsc-3.6.3-intel16-mpi5/src/ksp/pc/interface/precon.c
>> [0]PETSC ERROR: #4 KSPSetUp() line 332 in
>>
>> /home/hgharti/lsoft/petsc-3.6.3-intel16-mpi5/src/ksp/ksp/interface/itfunc.c
>> [0]PETSC ERROR: #5 KSPSolve() line 546 in
>>
>> /home/hgharti/lsoft/petsc-3.6.3-intel16-mpi5/src/ksp/ksp/interface/itfunc.c
>> forrtl: error (76): Abort trap signal
>>
>> Am I missing something?
>>
>> Thanks,
>> Hom Nath
>>
>> On Tue, Feb 2, 2016 at 3:24 PM, Matthew Knepley <knepley at gmail.com> wrote:
>> > On Tue, Feb 2, 2016 at 2:20 PM, Hom Nath Gharti <hng.email at gmail.com>
>> > wrote:
>> >>
>> >> Hi Matt, hi all,
>> >>
>> >> I am trying to use PCFIELDSPLIT for my solver which consists of 4
>> >> different variables, namely, u (displacement vector), \chi
>> >> (displacement potential), p(pressure), and \phi (gravity potential).
>> >>
>> >> My code segment looks like the following:
>> >> ======================================================
>> >> call KSPCreate(PETSC_COMM_WORLD,ksp,ierr)
>> >> call KSPGetPC(ksp,pc,ierr)
>> >> nsplit=4
>> >> call PCFieldSplitSetBlockSize(pc,nsplit,ierr);
>> >
>> >
>> > You do not need the statement above.
>> >
>> >>
>> >> call PCFieldSplitSetIS(pc,"0",gdofu_is,ierr);
>> >> call ISDestroy(gdofu_is,ierr)
>> >> call PCFieldSplitSetIS(pc,"1",gdofchi_is,ierr);
>> >> call ISDestroy(gdofchi_is,ierr)
>> >> call PCFieldSplitSetIS(pc,"2",gdofp_is,ierr);
>> >> call ISDestroy(gdofp_is,ierr)
>> >> call PCFieldSplitSetIS(pc,"3",gdofphi_is,ierr);
>> >> call ISDestroy(gdofphi_is,ierr)
>> >>
>> >> call PCFieldSplitGetSubKSP(pc,nsplit,subksp,ierr);
>> >
>> >
>> > These SetOperators() calls are wrong. I am not sure why you want them
>> > here.
>> > Also, that means you do not need the call above.
>> >
>> >   Thanks,
>> >
>> >      Matt
>> >
>> >>
>> >> call KSPSetOperators(subksp(1),Amat,Amat,ierr);
>> >> call KSPSetOperators(subksp(2),Amat,Amat,ierr);
>> >> call KSPSetOperators(subksp(3),Amat,Amat,ierr);
>> >> call KSPSetOperators(subksp(4),Amat,Amat,ierr);
>> >>
>> >> call KSPSolve(ksp,bvec,xvec,ierr)
>> >> ======================================================
>> >>
>> >> But I am getting the following error:
>> >> [79]PETSC ERROR: Null argument, when expecting valid pointer
>> >> [79]PETSC ERROR: Null Object: Parameter # 1
>> >> [79]PETSC ERROR: #1 KSPSetOperators() line 536 in
>> >> /home/hgharti/lsoft/petsc-3.6.3-intel16-mpi5/src/ksp/ksp/interf
>> >>
>> >> It looks like I am doing something wrong in "call KSPSetOperators" but
>> >> I could not figure that out.
>> >>
>> >> Could anybody help me to fix this problem? I looked into almost all
>> >> related examples but I could not really figure out the correct steps
>> >> after "call PCFieldSplitSetIS".
>> >>
>> >> Any help will be greatly appreciated.
>> >>
>> >> Best,
>> >> Hom nath
>> >>
>> >> On Sun, Jan 24, 2016 at 7:14 PM, Hom Nath Gharti <hng.email at gmail.com>
>> >> wrote:
>> >> > Thank you so much Matt! I will try.
>> >> >
>> >> > Hom Nath
>> >> >
>> >> > On Sun, Jan 24, 2016 at 6:26 AM, Matthew Knepley <knepley at gmail.com>
>> >> > wrote:
>> >> >> On Fri, Jan 22, 2016 at 2:19 PM, Hom Nath Gharti
>> >> >> <hng.email at gmail.com>
>> >> >> wrote:
>> >> >>>
>> >> >>> Dear all,
>> >> >>>
>> >> >>> I am new to PcFieldSplit.
>> >> >>>
>> >> >>> I have a matrix formed using MATMPIAIJ. Is it possible to use
>> >> >>> PCFIELDSPLIT operations in this type of matrix? Or does it have to
>> >> >>> be
>> >> >>> MATMPIBIJ or MATNEST format?
>> >> >>
>> >> >>
>> >> >> Yes, you can split AIJ.
>> >> >>
>> >> >>>
>> >> >>> If possible for MATMPIAIJ, could anybody provide me a simple
>> >> >>> example
>> >> >>> or few steps? Variables in the equations are displacement vector,
>> >> >>> scalar potential and pressure.
>> >> >>
>> >> >>
>> >> >> If you do not have a collocated discretization, then you have to use
>> >> >>
>> >> >>
>> >> >>
>> >> >>
>> >> >> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PC/PCFieldSplitSetIS.html
>> >> >>
>> >> >>   Thanks,
>> >> >>
>> >> >>      Matt
>> >> >>
>> >> >>>
>> >> >>> Thanks for help.
>> >> >>>
>> >> >>> Hom Nath
>> >> >>
>> >> >>
>> >> >>
>> >> >>
>> >> >> --
>> >> >> 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
>> >
>> >
>> >
>> >
>> > --
>> > 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
>
>
>
>
> --
> 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