[petsc-users] ISCreateStride and MatGetSubmatrices

[Jed Brown]

On Tue, Aug 28, 2012 at 10:33 AM, shu guo <greatgs2008 at gmail.com> wrote:

> Dear All,
>
> I want to extract a sequential matrix from a MPIBAIJ matrix A with a
> dimension of 4n*4n. After assembly A, I use ISCreateStride to define
> the index by
>
>           call ISCreateStride(PETSC_COMM_WORLD,n,0,1,isrow,ierr)
>

Fortran does not do type conversion without interfaces (which are about as
much hassle as benefit). If you configured PETSc with non-default integer
sizes, be sure to declare PetscInt zero,one instead of using numeric
literals.

Otherwise, run in valgrind to check that there isn't earlier corruption and
run in a debugger to get a stack trace.


>
> And extract the matrix as
>           call MatGetSubMatrices(Kmatem,1,isrow,isrow,
>      &                           MAT_INITIAL_MATRIX,Kmatemseq)
>
> But it gives me a segmentation fault when I call ISCreateStride. Is
> there anything I did wrong? Thanks for any advice.
>
> Shu
>
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