subroutine sum(x, res)
  implicit none
  real, intent(in) :: x(:)
  real, intent(out) :: res

  integer :: i

  !print *, "sum: size(x) = ", size(x)

  res = 0.0

  do i = 1, size(x)
    res = res + x(i)
  enddo

end subroutine sum

function fsum(x) result (res)
  implicit none
  real, intent(in) :: x(:)
  real :: res

  integer :: i

  !print *, "fsum: size(x) = ", size(x)

  res = 0.0

  do i = 1, size(x)
    res = res + x(i)
  enddo

end function fsum