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> 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> 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
>
>
>
