1: !
  2: !
  3: !    Fortran kernel for sparse matrix-vector product in the AIJ format
  4: !
  5: #include <petsc/finclude/petscsys.h>
  6: !
  7: pure subroutine FortranMultAddAIJ(n,x,ii,jj,a,y,z)
  8:   use, intrinsic :: ISO_C_binding
  9:   implicit none (type, external)
 10:   PetscScalar, intent(in) :: x(0:*),a(0:*),y(*)
 11:   PetscScalar, intent(inout) :: z(*)
 12:   PetscInt, intent(in) :: n,ii(*),jj(0:*)

 14:   PetscInt :: i,jstart,jend

 16:   jend  = ii(1)
 17:   do i=1,n
 18:     jstart = jend
 19:     jend   = ii(i+1)
 20:     z(i) = y(i) + sum(a(jstart:jend-1)*x(jj(jstart:jend-1)))
 21:   end do
 22: end subroutine FortranMultAddAIJ