You could try this: integer :: i real :: r i = loc(r) print *, i On Fri, Nov 19, 2021 at 12:34 AM 袁煕 <[email protected]> wrote:
Dear PETSc-team,
I am using function PetscSFGetGraph in my program like ----------------------- call PetscSFGetGraph(sf,gnroots,gnleaves,gmine,gremote,ierr) -----------------------
In some cases, it works well. But in some cases, I encountered following error ------------------ PETSC ERROR: Caught signal number 11 SEGV: Segmentation Violation, probably memory access out of range
------------------
I found it is due to the action of reading gmine, which is a fortran pointer point to an array. It is reasonable because PETSc manual tells me "if returned value is NULL, it means leaves are in contiguous storage". The problem is that I cannot find if gmine is a null pointer.
1) I cannot use "if (gmine==PETSC_NULL_INTEGER)" because my intel compiler would return a compile error "A scalar-valued expression is required in this context"
2) When using standard style of checking a null pointer in fortran, "associated(gmine)", it returns "T". Even in cases such action of "print *, gmine(1)" would give rise to above Segmentation Violation error.
Is there any means to check the NULL pointer in Fortran in above cases.
Many thanks,
Yuan