anchor.diff:            T_converged = .false.
             do while (.not. T_converged)
                ! Integrate T
  -             call do_timestep_T(s, dt_T, T_converged, delta_T_max)
  +             call do_timestep_T(s, minval(dt_T), T_converged, delta_T_max)
                            
                ! Increment time, number of iterations
  -             t = t + dt_T
  +             t = t + minval(dt_T)
                iteration = iteration + 1
                
                if (mod(iteration, output_freq) == 0) then
  
positive.code:           end do
            ! Recompute variables when the system is stable
            call compute_variables(s)
         end if
      else
         iteration = n_iterations
  
negative.code:   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_nu, t_T
    real(kind = x_precision), dimension(n_cell) :: dt_nu, dt_T
    logical                                     :: T_converged
    
  
    ! FIXME
    S_crit = 1.e99_x_precision
  