anchor.diff:           end do
   
         end do
  - 
  +
      end subroutine compute_force
  - 
  +
      subroutine compute_energy (m, r, v, Ec, Ep, E)
         implicit none
   
         real(kind=xp), dimension(:),    intent(in) :: m
         real(kind=xp), dimension(:, :), intent(in) :: r, v
  -     
  +
         real(kind=xp), intent(out) :: Ec, Ep, E
  -     
  +
         integer :: i, j
   
         Ec = 0._xp
  
positive.code:       epsilon2 = npoints**(2._xp/3._xp) / 400._xp
  
     end subroutine compute_initial_variables
     
     subroutine compute_force (m, r, a)
        implicit none
  
        real(kind=xp), dimension(:),    intent(in)  :: m
        real(kind=xp), dimension(:, :), intent(in)  :: r
    
        real(kind=xp), dimension(:, :), intent(out) :: a
    
        real(kind=xp), dimension(3) :: vec, tmp
        integer :: i, j
    
        a = 0._xp
  
        do i = 1, npoints
  
negative.code: 
        real(kind = xp), dimension(:, :), intent(in)  :: r
        real(kind = xp), dimension(:, :), intent(out) :: v
  
        real(kind = xp) :: omega
  
        omega = 0.5_xp / pi
        v(:, 1) =   omega * r(:, 2)
        v(:, 2) = - omega * r(:, 1)
        v(:, 3) = 0._xp
  
     end subroutine initial_speeds
  
     subroutine compute_initial_variables()
        implicit none
  
  