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

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

 13:   PetscCallA(PetscInitialize(ierr))
 14:   zero = 0
 15:   one = 1
 16:   n = 3
 17:   m = n
 18:   PetscCallA(MatCreateAIJ(PETSC_COMM_WORLD, PETSC_DECIDE, PETSC_DECIDE, n, m, one, PETSC_NULL_INTEGER_ARRAY, zero, PETSC_NULL_INTEGER_ARRAY, A, ierr))

 20:   PetscCallA(MatGetOwnershipRange(A, nl1, nl2, ierr))
 21:   do i = nl1, nl2 - 1
 22:     idxn(1) = i
 23:     idxm(1) = i
 24:     v(1) = 1.0
 25:     PetscCallA(MatSetValues(A, one, idxn, one, idxm, v, INSERT_VALUES, ierr))
 26:   end do
 27:   PetscCallA(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY, ierr))
 28:   PetscCallA(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY, ierr))

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

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

 42:   if ((idxn(1) >= nl1) .and. (idxn(1) <= nl2 - 1)) then
 43:     PetscCallA(MatGetValues(A, one, idxn, one, idxm, v, ierr))
 44:     write (6, *) PetscRealPart(v)
 45:   end if

 47:   PetscCallA(ISCreateStride(PETSC_COMM_WORLD, nl2 - nl1, nl1, one, is, ierr))
 48:   PetscCallA(ISLocalToGlobalMappingCreateIS(is, ismap, ierr))
 49:   PetscCallA(MatSetLocalToGlobalMapping(A, ismap, ismap, ierr))
 50:   PetscCallA(ISLocalToGlobalMappingDestroy(ismap, ierr))
 51:   PetscCallA(ISDestroy(is, ierr))
 52:   PetscCallA(MatGetValuesLocal(A, one, [zero], one, [zero], value, ierr))
 53:   PetscCallA(MatGetValuesLocal(A, one, [zero], one, [zero], values, ierr))
 54:   idxn(1) = 0
 55:   PetscCallA(MatGetValuesLocal(A, one, idxn, one, [zero], values, ierr))
 56:   PetscCallA(MatGetValuesLocal(A, one, idxn, one, idxn, values, ierr))

 58:   PetscCallA(MatDestroy(A, ierr))
 59:   PetscCallA(PetscFinalize(ierr))

 61: end program newnonzero

 63: !/*TEST
 64: !
 65: !     test:
 66: !       nsize: 2
 67: !       filter: Error:
 68: !
 69: !     test:
 70: !       requires: defined(PETSC_USE_INFO)
 71: !       suffix: 2
 72: !       nsize: 2
 73: !       args: -info
 74: !       filter: grep "Skipping"
 75: !
 76: !TEST*/