Actual source code: fmultadd.F90

  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