Added in barry/2023-05-04/add-pcgasm-set-subdomains see also https://gitlab.com/petsc/petsc/-/merge_requests/6419
Barry > On May 4, 2023, at 11:23 AM, LEONARDO MUTTI > <leonardo.mutt...@universitadipavia.it> wrote: > > Thank you for the help. > Adding to my example: > call PCGASMSetSubdomains(pc,NSub, subdomains_IS, inflated_IS,ierr) > call PCGASMDestroySubdomains(NSub,subdomains_IS,inflated_IS,ierr) > results in: > Error LNK2019 unresolved external symbol PCGASMDESTROYSUBDOMAINS > referenced in function ... > Error LNK2019 unresolved external symbol PCGASMSETSUBDOMAINS referenced > in function ... > I'm not sure if the interfaces are missing or if I have a compilation problem. > Thank you again. > Best, > Leonardo > > Il giorno sab 29 apr 2023 alle ore 20:30 Barry Smith <bsm...@petsc.dev > <mailto:bsm...@petsc.dev>> ha scritto: >> >> Thank you for the test code. I have a fix in the branch >> barry/2023-04-29/fix-pcasmcreatesubdomains2d >> <https://gitlab.com/petsc/petsc/-/commits/barry/2023-04-29/fix-pcasmcreatesubdomains2d> >> with merge request https://gitlab.com/petsc/petsc/-/merge_requests/6394 >> >> The functions did not have proper Fortran stubs and interfaces so I had >> to provide them manually in the new branch. >> >> Use >> >> git fetch >> git checkout barry/2023-04-29/fix-pcasmcreatesubdomains2d >> <https://gitlab.com/petsc/petsc/-/commits/barry/2023-04-29/fix-pcasmcreatesubdomains2d> >> ./configure etc >> >> Your now working test code is in src/ksp/ksp/tests/ex71f.F90 I had to >> change things slightly and I updated the error handling for the latest >> version. >> >> Please let us know if you have any later questions. >> >> Barry >> >> >> >> >>> On Apr 28, 2023, at 12:07 PM, LEONARDO MUTTI >>> <leonardo.mutt...@universitadipavia.it >>> <mailto:leonardo.mutt...@universitadipavia.it>> wrote: >>> >>> Hello. I am having a hard time understanding the index sets to feed >>> PCGASMSetSubdomains, and I am working in Fortran (as a PETSc novice). To >>> get more intuition on how the IS objects behave I tried the following >>> minimal (non) working example, which should tile a 16x16 matrix into 16 >>> square, non-overlapping submatrices: >>> >>> #include <petsc/finclude/petscmat.h> >>> #include <petsc/finclude/petscksp.h> >>> #include <petsc/finclude/petscpc.h> >>> USE petscmat >>> USE petscksp >>> USE petscpc >>> >>> Mat :: A >>> PetscInt :: M, NSubx, dof, overlap, NSub >>> INTEGER :: I,J >>> PetscErrorCode :: ierr >>> PetscScalar :: v >>> KSP :: ksp >>> PC :: pc >>> IS :: subdomains_IS, inflated_IS >>> >>> call PetscInitialize(PETSC_NULL_CHARACTER , ierr) >>> >>> !-----Create a dummy matrix >>> M = 16 >>> call MatCreateAIJ(MPI_COMM_WORLD, PETSC_DECIDE, PETSC_DECIDE, >>> & M, M, >>> & PETSC_DEFAULT_INTEGER, PETSC_NULL_INTEGER, >>> & PETSC_DEFAULT_INTEGER, PETSC_NULL_INTEGER, >>> & A, ierr) >>> >>> DO I=1,M >>> DO J=1,M >>> v = I*J >>> CALL MatSetValue (A,I-1,J-1,v, >>> & INSERT_VALUES , ierr) >>> END DO >>> END DO >>> >>> call MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY , ierr) >>> call MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY , ierr) >>> >>> !-----Create KSP and PC >>> call KSPCreate(PETSC_COMM_WORLD,ksp, ierr) >>> call KSPSetOperators(ksp,A,A, ierr) >>> call KSPSetType(ksp,"bcgs",ierr) >>> call KSPGetPC(ksp,pc,ierr) >>> call KSPSetUp(ksp, ierr) >>> call PCSetType(pc,PCGASM, ierr) >>> call PCSetUp(pc , ierr) >>> >>> !-----GASM setup >>> NSubx = 4 >>> dof = 1 >>> overlap = 0 >>> >>> call PCGASMCreateSubdomains2D(pc, >>> & M, M, >>> & NSubx, NSubx, >>> & dof, overlap, >>> & NSub, subdomains_IS, inflated_IS, ierr) >>> >>> call ISView(subdomains_IS, PETSC_VIEWER_STDOUT_WORLD, ierr) >>> >>> call KSPDestroy(ksp, ierr) >>> call PetscFinalize(ierr) >>> >>> Running this on one processor, I get NSub = 4. >>> If PCASM and PCASMCreateSubdomains2D are used instead, I get NSub = 16 as >>> expected. >>> Moreover, I get in the end "forrtl: severe (157): Program Exception - >>> access violation". So: >>> 1) why do I get two different results with ASM, and GASM? >>> 2) why do I get access violation and how can I solve this? >>> In fact, in C, subdomains_IS, inflated_IS should pointers to IS objects. As >>> I see on the Fortran interface, the arguments to PCGASMCreateSubdomains2D >>> are IS objects: >>> >>> subroutine PCGASMCreateSubdomains2D(a,b,c,d,e,f,g,h,i,j,z) >>> import tPC,tIS >>> PC a ! PC >>> PetscInt b ! PetscInt >>> PetscInt c ! PetscInt >>> PetscInt d ! PetscInt >>> PetscInt e ! PetscInt >>> PetscInt f ! PetscInt >>> PetscInt g ! PetscInt >>> PetscInt h ! PetscInt >>> IS i ! IS >>> IS j ! IS >>> PetscErrorCode z >>> end subroutine PCGASMCreateSubdomains2D >>> Thus: >>> 3) what should be inside e.g., subdomains_IS? I expect it to contain, for >>> every created subdomain, the list of rows and columns defining the subblock >>> in the matrix, am I right? >>> >>> Context: I have a block-tridiagonal system arising from space-time finite >>> elements, and I want to solve it with GMRES+PCGASM preconditioner, where >>> each overlapping submatrix is on the diagonal and of size 3x3 blocks (and >>> spanning multiple processes). This is PETSc 3.17.1 on Windows. >>> >>> Thanks in advance, >>> Leonardo >>
