I'm trying to understand how to assemble a block matrix in a format-independent manner, so that I can switch between types mpiaij and matnest.
The manual states that the key to format-independent assembly is to use MatGetLocalSubMatrix. So, in the code below, I'm using this to assemble a 3-by-3 block matrix A and setting the diagonal of block A02. This seems to work for type mpiaij, but not for type matnest. What am I missing? Chris $ cat mattry.F90 program mattry use petscksp implicit none #include <petsc/finclude/petsckspdef.h> PetscInt :: n=4 ! setting 4 cells per process PetscErrorCode :: ierr PetscInt :: size,rank,i Mat :: A,A02 IS :: isg0,isg1,isg2 IS :: isl0,isl1,isl2 ISLocalToGlobalMapping :: map integer, allocatable, dimension(:) :: idx call PetscInitialize(PETSC_NULL_CHARACTER,ierr); CHKERRQ(ierr) call MPI_Comm_size(PETSC_COMM_WORLD,size,ierr); CHKERRQ(ierr) call MPI_Comm_rank(PETSC_COMM_WORLD,rank,ierr);CHKERRQ(ierr) ! local index sets for 3 fields allocate(idx(n)) idx=(/ (i-1, i=1,n) /) call ISCreateGeneral(PETSC_COMM_WORLD,n,idx,PETSC_COPY_VALUES,isl0,ierr);CHKERRQ(ierr) call ISCreateGeneral(PETSC_COMM_WORLD,n,idx+n,PETSC_COPY_VALUES,isl1,ierr);CHKERRQ(ierr) call ISCreateGeneral(PETSC_COMM_WORLD,n,idx+2*n,PETSC_COPY_VALUES,isl2,ierr);CHKERRQ(ierr) ! call ISView(isl3,PETSC_VIEWER_STDOUT_WORLD,ierr); CHKERRQ(ierr) deallocate(idx) ! global index sets for 3 fields allocate(idx(n)) idx=(/ (i-1+rank*3*n, i=1,n) /) call ISCreateGeneral(PETSC_COMM_WORLD,n,idx,PETSC_COPY_VALUES,isg0,ierr);CHKERRQ(ierr) call ISCreateGeneral(PETSC_COMM_WORLD,n,idx+n,PETSC_COPY_VALUES,isg1,ierr); CHKERRQ(ierr) call ISCreateGeneral(PETSC_COMM_WORLD,n,idx+2*n,PETSC_COPY_VALUES,isg2,ierr); CHKERRQ(ierr) ! call ISView(isg3,PETSC_VIEWER_STDOUT_WORLD,ierr); CHKERRQ(ierr) deallocate(idx) ! local-to-global mapping allocate(idx(3*n)) idx=(/ (i-1+rank*3*n, i=1,3*n) /) call ISLocalToGlobalMappingCreate(PETSC_COMM_WORLD,1,3*n,idx,PETSC_COPY_VALUES,map,ierr); CHKERRQ(ierr) ! call ISLocalToGlobalMappingView(map,PETSC_VIEWER_STDOUT_WORLD,ierr); CHKERRQ(ierr) deallocate(idx) ! create the 3-by-3 block matrix call MatCreate(PETSC_COMM_WORLD,A,ierr); CHKERRQ(ierr) call MatSetSizes(A,3*n,3*n,PETSC_DECIDE,PETSC_DECIDE,ierr); CHKERRQ(ierr) ! call MatSetType(A,MATNEST,ierr); CHKERRQ(ierr) call MatSetUp(A,ierr); CHKERRQ(ierr) call MatSetOptionsPrefix(A,"A_",ierr); CHKERRQ(ierr) call MatSetLocalToGlobalMapping(A,map,map,ierr); CHKERRQ(ierr) call MatSetFromOptions(A,ierr); CHKERRQ(ierr) ! set diagonal of block A02 to 0.65 call MatGetLocalSubmatrix(A,isl0,isl2,A02,ierr); CHKERRQ(ierr) do i=1,n call MatSetValuesLocal(A02,1,i-1,1,i-1,0.65d0,INSERT_VALUES,ierr); CHKERRQ(ierr) end do call MatRestoreLocalSubMatrix(A,isl0,isl2,A02,ierr); CHKERRQ(ierr) call MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY,ierr); CHKERRQ(ierr) call MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY,ierr); CHKERRQ(ierr) ! verify call MatGetSubmatrix(A,isg0,isg2,MAT_INITIAL_MATRIX,A02,ierr); CHKERRQ(ierr) call MatView(A02,PETSC_VIEWER_STDOUT_WORLD,ierr);CHKERRQ(ierr) call PetscFinalize(ierr) end program mattry $ mpiexec -n 2 ./mattry -A_mat_type mpiaij Mat Object: 2 MPI processes type: mpiaij row 0: (0, 0.65) row 1: (1, 0.65) row 2: (2, 0.65) row 3: (3, 0.65) row 4: (4, 0.65) row 5: (5, 0.65) row 6: (6, 0.65) row 7: (7, 0.65) $ mpiexec -n 2 ./mattry -A_mat_type nest [0]PETSC ERROR: --------------------- Error Message -------------------------------------------------------------- [0]PETSC ERROR: Null argument, when expecting valid pointer [0]PETSC ERROR: Null Pointer: Parameter # 3 [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting. [0]PETSC ERROR: Petsc Release Version 3.7.3, Jul, 24, 2016 [0]PETSC ERROR: ./mattry on a linux_64bit_debug named lin0322.marin.local by cklaij Thu Jul 28 10:31:04 2016 [0]PETSC ERROR: Configure options --with-mpi-dir=/home/cklaij/ReFRESCO/Dev/trunk/Libs/install/openmpi/1.8.7 --with-clanguage=c++ --with-x=1 --with-debugging=1 --with-blas-lapack-dir=/opt/intel/composer_xe_2015.1.133/mkl --with-shared-libraries=0 [0]PETSC ERROR: #1 MatNestFindIS() line 298 in /home/cklaij/ReFRESCO/Dev/trunk/Libs/build/petsc/3.7.3-dbg/src/mat/impls/nest/matnest.c [0]PETSC ERROR: [1]PETSC ERROR: --------------------- Error Message -------------------------------------------------------------- [1]PETSC ERROR: Null argument, when expecting valid pointer [1]PETSC ERROR: Null Pointer: Parameter # 3 [1]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting. [1]PETSC ERROR: Petsc Release Version 3.7.3, Jul, 24, 2016 [1]PETSC ERROR: ./mattry on a linux_64bit_debug named lin0322.marin.local by cklaij Thu Jul 28 10:31:04 2016 [1]PETSC ERROR: Configure options --with-mpi-dir=/home/cklaij/ReFRESCO/Dev/trunk/Libs/install/openmpi/1.8.7 --with-clanguage=c++ --with-x=1 --with-debugging=1 --with-blas-lapack-dir=/opt/intel/composer_xe_2015.1.133/mkl --with-shared-libraries=0 [1]PETSC ERROR: #1 MatNestFindIS() line 298 in /home/cklaij/ReFRESCO/Dev/trunk/Libs/build/petsc/3.7.3-dbg/src/mat/impls/nest/matnest.c [1]PETSC ERROR: #2 MatNestFindSubMat() line 371 in /home/cklaij/ReFRESCO/Dev/trunk/Libs/build/petsc/3.7.3-dbg/src/mat/impls/nest/matnest.c [1]PETSC ERROR: #3 MatGetLocalSubMatrix_Nest() line 414 in /home/cklaij/ReFRESCO/Dev/trunk/Libs/build/petsc/3.7.3-dbg/src/mat/impls/nest/matnest.c [1]PETSC ERROR: #4 MatGetLocalSubMatrix() line 10099 in /home/cklaij/ReFRESCO/Dev/trunk/Libs/build/petsc/3.7.3-dbg/src/mat/interface/matrix.c #2 MatNestFindSubMat() line 371 in /home/cklaij/ReFRESCO/Dev/trunk/Libs/build/petsc/3.7.3-dbg/src/mat/impls/nest/matnest.c [0]PETSC ERROR: #3 MatGetLocalSubMatrix_Nest() line 414 in /home/cklaij/ReFRESCO/Dev/trunk/Libs/build/petsc/3.7.3-dbg/src/mat/impls/nest/matnest.c [0]PETSC ERROR: #4 MatGetLocalSubMatrix() line 10099 in /home/cklaij/ReFRESCO/Dev/trunk/Libs/build/petsc/3.7.3-dbg/src/mat/interface/matrix.c -------------------------------------------------------------------------- MPI_ABORT was invoked on rank 1 in communicator MPI_COMM_WORLD with errorcode 85. NOTE: invoking MPI_ABORT causes Open MPI to kill all MPI processes. You may or may not see output from other processes, depending on exactly when Open MPI kills them. -------------------------------------------------------------------------- [lin0322.marin.local:11985] 1 more process has sent help message help-mpi-api.txt / mpi-abort [lin0322.marin.local:11985] Set MCA parameter "orte_base_help_aggregate" to 0 to see all help / error messages $ dr. ir. Christiaan Klaij | CFD Researcher | Research & Development MARIN | T +31 317 49 33 44 | mailto:c.kl...@marin.nl | http://www.marin.nl MARIN news: http://www.marin.nl/web/News/News-items/Ship-design-in-EU-project-Holiship.htm