[petsc-users] PCFIELDSPLIT question
Matthew Knepley
knepley at gmail.com
Thu Feb 11 12:34:20 CST 2016
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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20160211/7ecdcabc/attachment-0001.html>
More information about the petsc-users
mailing list