anchor.diff:    type(state)                                 :: s
     real(kind = x_precision)                    :: delta_S_max, delta_T_max, t
     real(kind = x_precision), dimension(n_cell) :: prev_S, S_crit
  -  real(kind = x_precision)                    :: t_V, t_T
  -  real(kind = x_precision)                    :: dt_V, dt_T
  +  real(kind = x_precision)                    :: t_nu, t_T
  +  real(kind = x_precision)                    :: dt_nu, dt_T
     logical                                     :: T_converged
   
     ! FIXME
  
positive.code:         prev_S = s%S
  
          ! Integrate S
          call do_timestep_S(s, dt_V)
  
          ! Recompute variables
          call compute_variables(s)
  
          ! Increment time, number of iterations
          t = t + dt_V
          iteration = iteration + 1
  
          ! Output things here
  
negative.code:   ! we multiply delta to prevent the code from thinking it converged
    prev_S = 1.2*s%S
  
    t_T  = params%t_T  !* state_0%temps_0
    t_nu = params%t_nu !*  state_0%temps_0
  
    dt_nu = t_nu / 100._x_precision
    dt_T  = t_T / 100._x_precision
  
    write(*,*) 'dt_T, dt_nu:', dt_T, dt_nu
  
    ! Initial time = 0
    t = 0._x_precision
  