1: #include <petsc/finclude/petscmat.h>
  2: program newnonzero
  3:   use petscmat
  4:   implicit none

  6:   Mat :: A
  7:   PetscInt, parameter :: n = 3, m = n
  8:   PetscInt :: idxm(1), idxn(1), nl1, nl2, i
  9:   PetscScalar :: v(1), value(1), values(2)
 10:   PetscErrorCode :: ierr
 11:   IS :: is
 12:   ISLocalToGlobalMapping :: ismap

 14:   PetscCallA(PetscInitialize(ierr))
 15:   PetscCallA(MatCreateAIJ(PETSC_COMM_WORLD, PETSC_DECIDE, PETSC_DECIDE, n, m, 1_PETSC_INT_KIND, PETSC_NULL_INTEGER_ARRAY, 0_PETSC_INT_KIND, PETSC_NULL_INTEGER_ARRAY, A, ierr))

 17:   PetscCallA(MatGetOwnershipRange(A, nl1, nl2, ierr))
 18:   do i = nl1, nl2 - 1
 19:     idxn(1) = i
 20:     idxm(1) = i
 21:     v(1) = 1.0
 22:     PetscCallA(MatSetValues(A, 1_PETSC_INT_KIND, idxn, 1_PETSC_INT_KIND, idxm, v, INSERT_VALUES, ierr))
 23:   end do
 24:   PetscCallA(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY, ierr))
 25:   PetscCallA(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY, ierr))

 27: ! Ignore any values set into new nonzero locations
 28:   PetscCallA(MatSetOption(A, MAT_NEW_NONZERO_LOCATIONS, PETSC_FALSE, ierr))

 30:   idxn(1) = 0
 31:   idxm(1) = n - 1
 32:   if ((idxn(1) >= nl1) .and. (idxn(1) <= nl2 - 1)) then
 33:     v(1) = 2.0
 34:     PetscCallA(MatSetValues(A, 1_PETSC_INT_KIND, idxn, 1_PETSC_INT_KIND, idxm, v, INSERT_VALUES, ierr))
 35:   end if
 36:   PetscCallA(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY, ierr))
 37:   PetscCallA(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY, ierr))

 39:   if ((idxn(1) >= nl1) .and. (idxn(1) <= nl2 - 1)) then
 40:     PetscCallA(MatGetValues(A, 1_PETSC_INT_KIND, idxn, 1_PETSC_INT_KIND, idxm, v, ierr))
 41:     write (6, *) PetscRealPart(v)
 42:   end if

 44:   PetscCallA(ISCreateStride(PETSC_COMM_WORLD, nl2 - nl1, nl1, 1_PETSC_INT_KIND, is, ierr))
 45:   PetscCallA(ISLocalToGlobalMappingCreateIS(is, ismap, ierr))
 46:   PetscCallA(MatSetLocalToGlobalMapping(A, ismap, ismap, ierr))
 47:   PetscCallA(ISLocalToGlobalMappingDestroy(ismap, ierr))
 48:   PetscCallA(ISDestroy(is, ierr))
 49:   PetscCallA(MatGetValuesLocal(A, 1_PETSC_INT_KIND, [0_PETSC_INT_KIND], 1_PETSC_INT_KIND, [0_PETSC_INT_KIND], value, ierr))
 50:   PetscCallA(MatGetValuesLocal(A, 1_PETSC_INT_KIND, [0_PETSC_INT_KIND], 1_PETSC_INT_KIND, [0_PETSC_INT_KIND], values, ierr))
 51:   idxn(1) = 0
 52:   PetscCallA(MatGetValuesLocal(A, 1_PETSC_INT_KIND, idxn, 1_PETSC_INT_KIND, [0_PETSC_INT_KIND], values, ierr))
 53:   PetscCallA(MatGetValuesLocal(A, 1_PETSC_INT_KIND, idxn, 1_PETSC_INT_KIND, idxn, values, ierr))

 55:   PetscCallA(MatDestroy(A, ierr))
 56:   PetscCallA(PetscFinalize(ierr))

 58: end program newnonzero

 60: !/*TEST
 61: !
 62: !     test:
 63: !       nsize: 2
 64: !       filter: Error:
 65: !
 66: !     test:
 67: !       requires: defined(PETSC_USE_INFO)
 68: !       suffix: 2
 69: !       nsize: 2
 70: !       args: -info
 71: !       filter: grep "Skipping"
 72: !
 73: !TEST*/