anchor.diff:    ps_t = 0.0_WP
     tot_t = 0.0_WP
   
  +  call mass_change
  +
     return
   end subroutine init
   
  
positive.code:   real(WP) :: total_time
    real(WP) :: twrite
  
    init_start = omp_get_wtime()
    time = 0.0_WP
    dt = 0.0_WP
  
negative.code:     l = nc(i)
      do j = 1, l
        nb = nbs(i,j)
        dx = px(i) - px(nb)
        dy = py(i) - py(nb)
        dz = pz(i) - pz(nb)
  