Thanks, Mark. Yes, it actually works when I update to ISLocalToGlobalMappingGetIndicesF90. I made a mistake reporting this does not work. Danyang From: Mark Adams <[email protected]> Date: Monday, May 8, 2023 at 7:22 PM To: Danyang Su <[email protected]> Cc: petsc-users <[email protected]> Subject: Re: [petsc-users] Question on ISLocalToGlobalMappingGetIndices Fortran Interface On Mon, May 8, 2023 at 6:50 PM Danyang Su <[email protected]> wrote: Dear PETSc-Users, Is there any changes in ISLocalToGlobalMappingGetIndices function after PETSc 3.17? In the previous PETSc version (<= 3.17), the function ‘ISLocalToGlobalMappingGetIndices(ltogm,ltog,idltog,ierr)’ works fine, even though the value of idltog looks out of bound (-11472655627481), https://www.mcs.anl.gov/petsc/petsc-3.14/src/ksp/ksp/tutorials/ex14f.F90.htm.... The value of idltog is not clear. In the latest PETSc version, this function can be called, but due to the extreme value of idltog, the code fails. I also tried to use ‘ISLocalToGlobalMappingGetIndicesF90(ltogm,ltog,ierr)’ () but no success. * You do want the latter: doc/changes/319.rst:- Deprecate ``ISLocalToGlobalMappingGetIndices()`` in favor of ``ISLocalToGlobalMappingGetIndicesF90()`` * You might look at a test: src/ksp/ksp/tutorials/ex14f.F90: PetscCall(ISLocalToGlobalMappingGetIndicesF90(ltogm,ltog,ierr)) * If you use 64 bit integers be careful. * You want to use a memory checker like Valgrind or Sanitize. Mark #if (PETSC_VERSION_MAJOR == 3 && PETSC_VERSION_MINOR <= 4) call DMDAGetGlobalIndicesF90(dmda_flow%da,PETSC_NULL_INTEGER, & idx,ierr) CHKERRQ(ierr) #else call DMGetLocalToGlobalMapping(dmda_flow%da,ltogm,ierr) CHKERRQ(ierr) call ISLocalToGlobalMappingGetIndices(ltogm,ltog,idltog,ierr) CHKERRQ(ierr) #endif dof = dmda_flow%dof do ivol = 1, nngl #if (PETSC_VERSION_MAJOR == 3 && PETSC_VERSION_MINOR <= 4) node_idx_lg2pg(ivol) = (idx(ivol*dof)+1)/dof #else node_idx_lg2pg(ivol) = (ltog(ivol*dof + idltog)+1)/dof #endif end do Any suggestions on that. Thanks, Danyang