[petsc-users] PCFIELDSPLIT question
Matthew Knepley
knepley at gmail.com
Tue Feb 9 09:36:15 CST 2016
On Tue, Feb 9, 2016 at 9:31 AM, Hom Nath Gharti <hng.email at gmail.com> wrote:
> Thanks a lot Matt!
>
> Were you referring to
>
> http://www.mcs.anl.gov/petsc/petsc-current/src/snes/examples/tutorials/ex62.c.html
> ?
>
> I do not see any statements related to PCFieldSplit there. Am I
> missing something here?
>
Yes. The whole point is not to put anything specific to FIELDSPLIT in the
code. It is all in options. For example,
./ex62 -run_type full -refinement_limit 0.00625 -bc_type dirichlet
-interpolate 1 -vel_petscspace_order 2 -pres_petscspace_order 1 -ksp_type
fgmres -ksp_gmres_restart 100 -ksp_rtol 1.0e-9 -pc_type fieldsplit
-pc_fieldsplit_type schur -pc_fieldsplit_schur_factorization_type upper
-fieldsplit_pressure_ksp_rtol 1e-10 -fieldsplit_velocity_ksp_type gmres
-fieldsplit_velocity_pc_type lu -fieldsplit_pressure_pc_type jacobi
-snes_monitor_short -ksp_monitor_short -snes_converged_reason
-ksp_converged_reason -snes_view -show_solution 0
The reason that it works is that the DM calls PCFIeldSplitSetIS() for each
field in the DM.
Thanks,
Matt
> Thanks,
> Hom Nath
>
> On Tue, Feb 9, 2016 at 10:19 AM, Matthew Knepley <knepley at gmail.com>
> wrote:
> > On Tue, Feb 9, 2016 at 9:10 AM, Hom Nath Gharti <hng.email at gmail.com>
> wrote:
> >>
> >> Thank you so much Barry!
> >>
> >> For my small test case, with -pc_fieldsplit_block_size 4, the program
> >> runs, although the answer was not correct. At least now I get
> >> something to look upon. I am using PCFieldSplitSetIS to set the
> >> fields. Do I still need to use -pc_fieldsplit_block_size?
> >
> >
> > No, this is only for co-located discretizations.
> >
> >>
> >> In my case each grid point may have different variable sets. For
> >> example, the grid point in the solid region has displacement and
> >> gravity potential: ux, uy, uz, and \phi. Whereas the grid point in the
> >> fluid region has scalar potential, pressure and gravity potential:
> >> \chi, p, and \phi. And the solid-fluid interface has all of them. Do
> >> you think I can still use PCFIELDSPLIT in this situation?
> >
> >
> > We have examples, like SNES ex62, which do exactly this.
> >
> > Thanks,
> >
> > Matt
> >
> >>
> >> Best,
> >> Hom Nath
> >>
> >>
> >>
> >> On Mon, Feb 8, 2016 at 2:27 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> >> >
> >> >
> >> > In this case you need to provide two pieces of information to the
> >> > PCFIELDSPLIT. What we call the "block size" or bs which is the number
> of
> >> > "basic fields" in the problem. For example if at each grid point you
> have
> >> > x-velocity, y-velocity, and pressure the block size is 3. The second
> is you
> >> > need to tell PCFIELDSPLIT what "basic fields" are in each split you
> want to
> >> > use.
> >> >
> >> > In your case you can do this with -pc_fieldsplit_block_size 4.
> >> > (Note if you use a DM to define your problem the PCFIELDSPLIT will
> >> > automatically get the bs from the DM so you do not need to provide it.
> >> > Similarly if you set a block size on your Mat the PCFIELDSPLIT will
> use that
> >> > so you don't need to set it).
> >> >
> >> > Then use -pc_fieldsplit_0_fields 0,1 to indicate your first split
> is
> >> > the 0 and 1 basic fields and -pc_fieldsplit_1_fields 2,3 to indicate
> the
> >> > second split is the 2 and 3 basic fields.
> >> > (By default if you do not provide this then PCFIELDSPLIT will use bs
> >> > splits (4 in your case) one for each basic field.
> >> >
> >> > Barry
> >> >
> >> >> On Feb 8, 2016, at 11:20 AM, Hom Nath Gharti <hng.email at gmail.com>
> >> >> wrote:
> >> >>
> >> >> Hi Matt, Hi all,
> >> >>
> >> >> I am trying to have some feel for PCFIELDSPLIT testing on a very
> small
> >> >> matrix (attached below). I have 4 degrees of freedoms. I use 4
> >> >> processors. I want to split 4 dofs into two fields each having two
> >> >> dofs. I don't know whether this my be a problem for petsc. When I use
> >> >> the command:
> >> >> srun -n 4 ./xtestfs -ksp_monitor -ksp_view
> >> >>
> >> >> It runs fine.
> >> >>
> >> >> But when I want to use field split options using the command:
> >> >> srun -n 4 ./xtestfs -ksp_monitor -ksp_type fgmres -pc_type fieldsplit
> >> >> -fieldsplit_0_ksp_type gmres -fieldsplit_0_pc_type bjacobi
> >> >> -fieldsplit_1_pc_type jacobi
> >> >>
> >> >> I get the following 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/test/testfs/./xtestfs on a
> >> >> arch-linux2-c-debug named tiger-r11n1 by hgharti Mon Feb 8 11:40:03
> >> >> 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 --with-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
> >> >> WARNING! There are options you set that were not used!
> >> >> WARNING! could be spelling mistake, etc!
> >> >> Option left: name:-fieldsplit_0_ksp_type value: gmres
> >> >> Option left: name:-fieldsplit_0_pc_type value: bjacobi
> >> >> Option left: name:-fieldsplit_1_pc_type value: jacobi
> >> >> forrtl: error (76): Abort trap signal
> >> >>
> >> >> I tried several trials but could not fix the problem. Is it the
> >> >> FORTRAN problem or am I doing something wrong? Any suggestions would
> >> >> be greatly appreciated.
> >> >> For your information I use:
> >> >> PETSc-3.6.3
> >> >> intel-16.0 compiler
> >> >> intel-mpi-5.1.1
> >> >>
> >> >> Program
> >> >>
> >> >>
> >> >> Best,
> >> >> Hom Nath
> >> >>
> >> >> ! simple test case for PCFIELDSPLIT
> >> >> !
> >> >>
> -----------------------------------------------------------------------
> >> >> program testfs
> >> >> implicit none
> >> >> #include "petsc/finclude/petscsys.h"
> >> >> #include "petsc/finclude/petscvec.h"
> >> >> #include "petsc/finclude/petscvec.h90"
> >> >> #include "petsc/finclude/petscmat.h"
> >> >> #include "petsc/finclude/petscksp.h"
> >> >> #include "petsc/finclude/petscpc.h"
> >> >> #include "petsc/finclude/petscviewer.h"
> >> >> #include "petsc/finclude/petscviewer.h90"
> >> >>
> >> >> Vec x,b,u
> >> >> Mat A
> >> >> KSP ksp
> >> >> PC pc
> >> >> PetscErrorCode ierr
> >> >> PetscBool flg
> >> >> PetscInt errcode,its,maxitr,myrank,nproc
> >> >> PetscInt nedof,nelmt,ndof,nenod,ngdof,fixdof,nsparse,neq
> >> >> PetscInt,allocatable :: krow_sparse(:),ggdof_elmt(:,:), &
> >> >> inode_elmt(:,:)
> >> >>
> >> >> PetscReal,allocatable :: storef(:,:),storekmat(:,:,:)
> >> >> PetscInt gdof0(2),gdof1(2)
> >> >>
> >> >> ! initialize MPI
> >> >>
> >> >> call MPI_INIT(errcode)
> >> >> if(errcode /= 0)stop 'ERROR: cannot initialize MPI!'
> >> >> call MPI_COMM_RANK(MPI_COMM_WORLD,myrank,errcode)
> >> >> if(errcode /= 0)stop 'ERROR: cannot find processor ID'
> >> >> call MPI_COMM_SIZE(MPI_COMM_WORLD,nproc,errcode)
> >> >> if(errcode /= 0)stop 'ERROR: cannot find number of processors!'
> >> >>
> >> >> ! define some parameters
> >> >> ! 1D model with 4 elements. Each elements consits of 2 nodes. Node 0
> is
> >> >> fixed.
> >> >> ! 1-----------2-----------3-----------4-----------5
> >> >> nelmt=1 ! per processor
> >> >> nenod=2 ! number of nodes per element
> >> >> nedof=2 ! number of DOFs per element
> >> >> ndof=2 ! number of DOFs
> >> >> ngdof=4 ! total number of global DOFs
> >> >> fixdof=1
> >> >>
> >> >> if(myrank==0)then
> >> >> neq=1 ! number of equations
> >> >> nsparse=1
> >> >> else
> >> >> neq=2 ! number of equations
> >> >> nsparse=4
> >> >> endif
> >> >>
> >> >> allocate(storef(nedof,nelmt),storekmat(nedof,nedof,nelmt),
> >> >> &
> >> >> ggdof_elmt(nedof,nelmt),inode_elmt(nenod,nelmt),krow_sparse(nsparse))
> >> >>
> >> >> storef=0.0_8 ! local RHS vector
> >> >> storekmat=0.0_8 ! local stiffness matrix
> >> >> if(myrank==0)then
> >> >> krow_sparse(:)=1
> >> >> storef(:,1)=(/12.5000_8, 12.5000_8/)
> >> >> storekmat(:,:,1) = reshape((/1.2333333332_8, 0.0166666667_8, &
> >> >> 0.0166666667_8,
> >> >> 1.2333333332_8/),(/nedof,nedof/))
> >> >> inode_elmt(:,1) = (/1,2/)
> >> >> ggdof_elmt(:,1) = (/0,1/) ! 0 because left node is fixed
> >> >> elseif(myrank==1)then
> >> >> krow_sparse(:)=(/1,1,2,2/)
> >> >> storef(:,1)=(/12.5000_8, 12.5000_8/)
> >> >> storekmat(:,:,1) = reshape((/1.2333333332_8, 0.0166666667_8, &
> >> >> 0.0166666667_8,
> >> >> 1.2333333332_8/),(/nedof,nedof/))
> >> >> inode_elmt(:,1) = (/1,2/)
> >> >> ggdof_elmt(:,1) = (/1,2/)
> >> >> elseif(myrank==2)then
> >> >> krow_sparse(:)=(/1,1,2,2/)
> >> >> storef(:,1)=(/12.5000_8, 12.5000_8/)
> >> >> storekmat(:,:,1) = reshape((/1.2333333332_8, 0.0166666667_8, &
> >> >> 0.0166666667_8,
> >> >> 1.2333333332_8/),(/nedof,nedof/))
> >> >> inode_elmt(:,1) = (/1,2/)
> >> >> ggdof_elmt(:,1) = (/2,3/)
> >> >> elseif(myrank==3)then
> >> >> krow_sparse(:)=(/1,1,2,2/)
> >> >> storef(:,1)=(/12.5000_8, 22.5000_8/)
> >> >> storekmat(:,:,1) = reshape((/1.2333333332_8, 0.0166666667_8, &
> >> >> 0.0166666667_8,
> >> >> 1.2333333332_8/),(/nedof,nedof/))
> >> >> inode_elmt(:,1) = (/1,2/)
> >> >> ggdof_elmt(:,1) = (/3,4/)
> >> >> endif
> >> >>
> >> >> call petsc_initialize
> >> >> call petsc_set_matrix
> >> >> call petsc_set_vector
> >> >> call petsc_solve
> >> >> call petsc_finalize
> >> >>
> >> >> ! deallocate
> >> >> deallocate(storef,storekmat,ggdof_elmt,inode_elmt)
> >> >> deallocate(krow_sparse)
> >> >> contains
> >> >>
> >> >>
> !-------------------------------------------------------------------------------
> >> >> subroutine petsc_initialize()
> >> >> implicit none
> >> >> PetscInt :: istart,iend
> >> >> PetscInt :: nzeros_max,nzeros_min
> >> >> PetscReal :: atol,dtol,rtol
> >> >> PetscInt,allocatable :: nzeros(:)
> >> >> IS gdof0_is,gdof1_is
> >> >>
> >> >> call PetscInitialize(PETSC_NULL_CHARACTER,ierr)
> >> >> call PetscOptionsGetInt(PETSC_NULL_CHARACTER,'-n',ngdof,flg,ierr)
> >> >>
> >> >> ! count number of nonzeros per row
> >> >> allocate(nzeros(neq))
> >> >> nzeros=0
> >> >> nzeros(krow_sparse)=nzeros(krow_sparse)+1
> >> >> nzeros_max=maxval(nzeros)
> >> >> nzeros_min=minval(nzeros)
> >> >>
> >> >> ! create matrix
> >> >> call MatCreate(PETSC_COMM_WORLD,A,ierr)
> >> >> call MatSetType(A,MATMPIAIJ,ierr)
> >> >> CHKERRQ(ierr)
> >> >> call MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,ngdof,ngdof,ierr)
> >> >> CHKERRQ(ierr)
> >> >> ! preallocation
> >> >> call
> >> >>
> MatMPIAIJSetPreallocation(A,nzeros_max,PETSC_NULL_INTEGER,nzeros_max, &
> >> >> PETSC_NULL_INTEGER,ierr)
> >> >> CHKERRQ(ierr)
> >> >>
> >> >> call MatGetOwnershipRange(A,istart,iend,ierr)
> >> >> CHKERRQ(ierr)
> >> >> print*,'ownership:',myrank,istart,iend
> >> >> ! create vector
> >> >> call VecCreate(PETSC_COMM_WORLD,x,ierr)
> >> >> call VecSetSizes(x,PETSC_DECIDE,ngdof,ierr)
> >> >> call VecSetType(x,VECMPI,ierr)
> >> >> call VecDuplicate(x,b,ierr)
> >> >> call VecDuplicate(x,u,ierr)
> >> >>
> >> >>
> >> >>
> !*******************************************************************************
> >> >> ! get IS for split fields
> >> >> gdof0=(/0,1/)
> >> >> gdof1=(/2,3/)
> >> >> call
> >> >>
> ISCreateGeneral(PETSC_COMM_WORLD,2,gdof0,PETSC_COPY_VALUES,gdof0_is,ierr)
> >> >> CHKERRQ(ierr)
> >> >> call
> >> >>
> ISCreateGeneral(PETSC_COMM_WORLD,2,gdof1,PETSC_COPY_VALUES,gdof1_is,ierr)
> >> >> CHKERRQ(ierr)
> >> >>
> >> >>
> !*******************************************************************************
> >> >>
> >> >> ! Create linear solver context
> >> >> call KSPCreate(PETSC_COMM_WORLD,ksp,ierr)
> >> >> call KSPSetOperators(ksp,A,A,ierr)
> >> >>
> >> >> call KSPGetPC(ksp,pc,ierr)
> >> >> CHKERRQ(ierr)
> >> >>
> >> >>
> >> >>
> !*******************************************************************************
> >> >> ! split PC
> >> >> call PCFieldSplitSetIS(pc,"0",gdof0_is,ierr);
> >> >> CHKERRQ(ierr)
> >> >> call ISDestroy(gdof0_is,ierr)
> >> >> CHKERRQ(ierr)
> >> >> call PCFieldSplitSetIS(pc,"1",gdof1_is,ierr);
> >> >> CHKERRQ(ierr)
> >> >> call ISDestroy(gdof1_is,ierr)
> >> >> CHKERRQ(ierr)
> >> >>
> >> >>
> !*******************************************************************************
> >> >>
> >> >> rtol = 1.0d-6
> >> >> atol = 1.0d-6
> >> >> dtol = 1.0d10
> >> >> maxitr = 1000
> >> >> call KSPSetTolerances(ksp,rtol,atol,dtol,maxitr,ierr)
> >> >> CHKERRQ(ierr)
> >> >> call KSPSetFromOptions(ksp,ierr)
> >> >> end subroutine petsc_initialize
> >> >>
> >> >>
> !-------------------------------------------------------------------------------
> >> >>
> >> >> subroutine petsc_set_matrix()
> >> >>
> >> >> implicit none
> >> >> integer :: i,i_elmt,j,ncount
> >> >> integer :: ggdof(NEDOF),idof(NEDOF),igdof(NEDOF)
> >> >>
> >> >> ! Set and assemble matrix.
> >> >> call MatZeroEntries(A,ierr)
> >> >> CHKERRQ(ierr)
> >> >> do i_elmt=1,nelmt
> >> >> ggdof(:)=ggdof_elmt(:,i_elmt)
> >> >> ggdof(:)=ggdof(:)-1 ! petsc index starts from 0
> >> >> ncount=0; idof=-1; igdof=-1
> >> >> do i=1,NEDOF
> >> >> do j=1,NEDOF
> >> >> if(ggdof(i).ge.0.and.ggdof(j).ge.0)then
> >> >> call MatSetValues(A,1,ggdof(i),1,ggdof(j),storekmat(i,j,i_elmt),
> >> >> &
> >> >> ADD_VALUES,ierr)
> >> >> CHKERRQ(ierr)
> >> >> endif
> >> >> enddo
> >> >> enddo
> >> >> enddo
> >> >> call MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY,ierr)
> >> >> call MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY,ierr)
> >> >> if(myrank==0)print*,'matrix setting & assembly complete!'
> >> >>
> >> >> end subroutine petsc_set_matrix
> >> >>
> >> >>
> !-------------------------------------------------------------------------------
> >> >>
> >> >> subroutine petsc_set_vector()
> >> >> implicit none
> >> >> PetscScalar zero
> >> >> integer :: i,i_elmt,ncount
> >> >> integer :: ggdof(NEDOF),idof(NEDOF),igdof(NEDOF)
> >> >>
> >> >> ! set vector
> >> >> zero=0.0_8
> >> >> call VecSet(b,zero,ierr)
> >> >> do i_elmt=1,nelmt
> >> >> ggdof(:)=ggdof_elmt(:,i_elmt)
> >> >> ggdof(:)=ggdof(:)-1 ! petsc index starts from 0
> >> >> ncount=0; idof=-1; igdof=-1
> >> >> do i=1,NEDOF
> >> >> if(ggdof(i).ge.0)then
> >> >> call
> VecSetValues(b,1,ggdof(i),storef(i,i_elmt),ADD_VALUES,ierr);
> >> >> CHKERRQ(ierr)
> >> >> endif
> >> >> enddo
> >> >> enddo
> >> >>
> >> >> ! assemble vector
> >> >> call VecAssemblyBegin(b,ierr)
> >> >> call VecAssemblyEnd(b,ierr)
> >> >> if(myrank==0)print*,'vector setting & assembly complete!'
> >> >>
> >> >> end subroutine petsc_set_vector
> >> >>
> >> >>
> !-------------------------------------------------------------------------------
> >> >>
> >> >> subroutine petsc_solve()
> >> >> implicit none
> >> >> PetscInt ireason
> >> >> PetscScalar a_v(1)
> >> >> PetscOffset a_i
> >> >> PetscInt n
> >> >> PetscReal,allocatable :: sdata(:)
> >> >>
> >> >> call VecGetSize(b,n,ierr)
> >> >> CHKERRQ(ierr)
> >> >> allocate(sdata(n))
> >> >> sdata=0.0_8
> >> >> call VecGetArray(b,a_v,a_i,ierr)
> >> >> CHKERRQ(ierr)
> >> >> sdata(1:n)=a_v(a_i+1:a_i+n)
> >> >> call VecRestoreArray(b,a_v,a_i,ierr)
> >> >> CHKERRQ(ierr)
> >> >> print*,'rhs:',sdata
> >> >>
> >> >> call KSPSolve(ksp,b,x,ierr)
> >> >> sdata=0.0_8
> >> >> call VecGetArray(x,a_v,a_i,ierr)
> >> >> CHKERRQ(ierr)
> >> >> sdata(1:n)=a_v(a_i+1:a_i+n)
> >> >> call VecRestoreArray(b,a_v,a_i,ierr)
> >> >> CHKERRQ(ierr)
> >> >> print*,'solution:',sdata
> >> >>
> >> >> ! Check convergence
> >> >> call KSPGetConvergedReason(ksp,ireason,ierr)
> >> >> if(myrank==0)print*,'converges reason',myrank,ireason
> >> >> call KSPGetIterationNumber(ksp,its,ierr)
> >> >> if(myrank==0)print*,'Iterations:',its
> >> >> deallocate(sdata)
> >> >> end subroutine petsc_solve
> >> >>
> >> >>
> !-------------------------------------------------------------------------------
> >> >>
> >> >> subroutine petsc_finalize()
> >> >> implicit none
> >> >>
> >> >> ! Free work space.
> >> >> call VecDestroy(x,ierr)
> >> >> call VecDestroy(u,ierr)
> >> >> call VecDestroy(b,ierr)
> >> >> call MatDestroy(A,ierr)
> >> >> call KSPDestroy(ksp,ierr)
> >> >> call PetscFinalize(ierr)
> >> >> CHKERRQ(ierr)
> >> >>
> >> >> end subroutine petsc_finalize
> >> >>
> >> >>
> !-------------------------------------------------------------------------------
> >> >>
> >> >> end program testfs
> >> >>
> >> >> On Tue, Feb 2, 2016 at 4:54 PM, Matthew Knepley <knepley at gmail.com>
> >> >> wrote:
> >> >>> On Tue, Feb 2, 2016 at 3:11 PM, Hom Nath Gharti <
> hng.email at gmail.com>
> >> >>> wrote:
> >> >>>>
> >> >>>> Thanks a lot. I will try.
> >> >>>
> >> >>>
> >> >>> Also, if you send a small test case, we can run it and tell you the
> >> >>> problem.
> >> >>>
> >> >>> Matt
> >> >>>
> >> >>>>
> >> >>>> Hom Nath
> >> >>>>
> >> >>>> On Tue, Feb 2, 2016 at 4:02 PM, Matthew Knepley <knepley at gmail.com
> >
> >> >>>> wrote:
> >> >>>>> On Tue, Feb 2, 2016 at 3:01 PM, Hom Nath Gharti
> >> >>>>> <hng.email at gmail.com>
> >> >>>>> wrote:
> >> >>>>>>
> >> >>>>>> Thanks again Matt. Unfortunately got the same errors with '0'. I
> >> >>>>>> think
> >> >>>>>> both are valid in Fortran.
> >> >>>>>
> >> >>>>>
> >> >>>>> Then you will have to go in the debugger and see why its not
> >> >>>>> creating 4
> >> >>>>> splits, since this is exactly
> >> >>>>> what it does in our tests. This is how all the SNES tests that I
> use
> >> >>>>> work. I
> >> >>>>> am sure its a Fortran
> >> >>>>> problem.
> >> >>>>>
> >> >>>>> Thanks,
> >> >>>>>
> >> >>>>> Matt
> >> >>>>>
> >> >>>>>>
> >> >>>>>> 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
> >> >>>>>
> >> >>>>>
> >> >>>>>
> >> >>>>>
> >> >>>>> --
> >> >>>>> 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
>
--
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
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