anchor.diff:            call compute_variables(s)
             call timestep (s,dt_T, dt_nu)
             call distance(s, dist, temperature_c, sigma_c)
  +          ! Condition to slow dt
  +          dist_crit = 1. !FIXME
  +          if (maxval(dist) .ge. maxval(dist_crit)) then 
  +             dt_T  = dist / dist_crit * dt_nu
  +             dt_nu = dist / dist_crit * dt_T
  +          endif
          end if
       else
          iteration = n_iterations
  
positive.code:   implicit none
  
    !--------------------------- Parameters for s_curve-----------------------
    real(kind = x_precision), parameter         :: eps_in = 1.e-8_x_precision  ! Precision required for the dichotomy
    real(kind = x_precision), parameter         :: Tmin   = 2.5e-2_x_precision
    real(kind = x_precision), parameter         :: Tmax   = 4.49e0_x_precision
    real(kind = x_precision), parameter         :: Smin   = 2.36e1_x_precision
  
negative.code:  ! real(kind = x_precision)                    :: t_nu, t_T
    real(kind = x_precision), dimension(n_cell) :: dt_nu, dt_T
    logical                                     :: T_converged
    real (kind = x_precision), dimension(n_cell):: dist, dist_crit
    
  
    ! FIXME
  