[petsc-users] Confusion with MatGetLocalSubMatrix

[Lawrence Mitchell]

On 19 Dec 2014, at 18:19, Lawrence Mitchell <lawrence.mitchell at imperial.ac.uk> wrote:

> ...
> 
>>> Calling MatGetLocalSubMatrix results in an error:
>>> 
>>> [0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
>>> [0]PETSC ERROR: Petsc has generated inconsistent data
>>> [0]PETSC ERROR: Blocksize of localtoglobalmapping 1 must match that of layout 2
>> 
>> Hmm, I'm concerned that this might not work right after some recent
>> changes to ISLocalToGlobalMapping.  Can you reproduce this with some
>> code I can run?
...

Here's one that doesn't try to destroy sections that don't exist, and endeavours to print block sizes of all the sub matrices.  I expect to see (2, 2), (2, 1), (1, 2) and (1, 1) I think.

Cheers,

Lawrence

#include <petsc.h>

int main(int argc, char **argv)
{
    PetscErrorCode ierr;
    DM v;
    DM p;
    DM pack;
    PetscInt rbs, cbs;
    PetscInt srbs, scbs;
    PetscInt i, j;
    Mat mat;
    Mat submat;
    IS *ises;

    MPI_Comm c;
    PetscInitialize(&argc, &argv, NULL, NULL);

    c = PETSC_COMM_WORLD;
    ierr = DMDACreate1d(c, DM_BOUNDARY_NONE, 10, 2, 1, NULL, &v); CHKERRQ(ierr);
    ierr = DMDACreate1d(c, DM_BOUNDARY_NONE, 10, 1, 1, NULL, &p); CHKERRQ(ierr);
    ierr = DMSetFromOptions(v); CHKERRQ(ierr);
    ierr = DMSetFromOptions(p); CHKERRQ(ierr);

    
    ierr = DMCreateMatrix(v, &mat); CHKERRQ(ierr);

    ierr = MatGetBlockSizes(mat, &rbs, &cbs); CHKERRQ(ierr);

    ierr = PetscPrintf(c, "Global Mat block size (%d, %d)\n", rbs, cbs); CHKERRQ(ierr);
    ierr = MatDestroy(&mat); CHKERRQ(ierr);

    ierr = DMCompositeCreate(c, &pack); CHKERRQ(ierr);

    ierr = DMCompositeAddDM(pack, v); CHKERRQ(ierr);
    ierr = DMCompositeAddDM(pack, p); CHKERRQ(ierr);
    ierr = DMSetFromOptions(pack); CHKERRQ(ierr);

    ierr = DMCompositeGetLocalISs(pack, &ises); CHKERRQ(ierr);

    ierr = DMCreateMatrix(pack, &mat); CHKERRQ(ierr);

    ierr = MatGetBlockSizes(mat, &rbs, &cbs); CHKERRQ(ierr);

    ierr = PetscPrintf(c, "Global Mat block size (%d, %d)\n", rbs, cbs); CHKERRQ(ierr);

    for (i=0; i < 2; i++ ) {
        for (j=0; j < 2; j++ ) {
            ierr = MatGetLocalSubMatrix(mat, ises[i], ises[j], &submat); CHKERRQ(ierr);
            ierr = MatGetBlockSizes(submat, &srbs, &scbs); CHKERRQ(ierr);
            ierr = PetscPrintf(c, "Local (%d, %d) block has block size (%d, %d)\n", i, j, srbs, scbs); CHKERRQ(ierr);
            ierr = MatDestroy(&submat); CHKERRQ(ierr);
        }
    }
    ierr = MatDestroy(&mat); CHKERRQ(ierr);

    ierr = DMDestroy(&pack); CHKERRQ(ierr);
    ierr = DMDestroy(&v); CHKERRQ(ierr);
    ierr = DMDestroy(&p); CHKERRQ(ierr);

    ierr = ISDestroy(&(ises[0])); CHKERRQ(ierr);
    ierr = ISDestroy(&(ises[1])); CHKERRQ(ierr);
    ierr = PetscFree(ises); CHKERRQ(ierr);

    PetscFinalize();

    return 0;
}
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 455 bytes
Desc: Message signed with OpenPGP using GPGMail
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20141219/75d4e86b/attachment.pgp>