[petsc-users] PCFIELDSPLIT question
Hom Nath Gharti
hng.email at gmail.com
Thu Feb 11 12:41:22 CST 2016
Perfect! Thanks a lot Matt!
Hom Nath
On Thu, Feb 11, 2016 at 1:34 PM, Matthew Knepley <knepley at gmail.com> wrote:
> On Thu, Feb 11, 2016 at 11:47 AM, Hom Nath Gharti <hng.email at gmail.com>
> wrote:
>>
>> Thanks all. With further help from Stefano Zhampini I was able to
>> solve my small test case using PCFieldSPlit option. I had to add
>> call PCSetType(pc,PCFIELDSPLIT,ierr)
>>
>> Now I am trying to use same technique in my actual problem and got the
>> error:
>>
>> PETSC ERROR: Fields must be sorted when creating split
>>
>> Does this mean I have to sort the global matrix rows according the split
>> fields?
>
>
> You have to sort the IS you pass to PCFieldSplitSetIS() which can be done
> using ISSort()
>
> Thanks,
>
> Matt
>
>>
>> Thanks
>> Hom Nath
>>
>>
>>
>> On Tue, Feb 9, 2016 at 10:57 AM, Hom Nath Gharti <hng.email at gmail.com>
>> wrote:
>> > Sounds interesting! Thanks a lot Matt! I will have a look.
>> >
>> > Hom Nath
>> >
>> > On Tue, Feb 9, 2016 at 10:36 AM, Matthew Knepley <knepley at gmail.com>
>> > wrote:
>> >> 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
>
>
>
>
> --
> 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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