anchor.diff:  
       j = 0
   
  -    call variables(T, Smin, Omega, f_min, optical_depth, tau_eff)
  -
  -    call variables(T, Smax, Omega, f_max, optical_depth, tau_eff)
  +    call variables(k, T, Smin, f_min, optical_depth, tau_eff)
  +
  +    call variables(k, T, Smax, f_max, optical_depth, tau_eff)
   
       !write(*,*)'fmin = ',f_min
       !write(*,*)'fmax = ',f_max
  
positive.code:     !------------------------------------------------------------------------
  
      do k = 1, n_cell
        omega = x_state%Omega(k)
  
        ! For each point of the S curve
        do i = 1, nb_it
          ! Optical thick case (tau >= 1)
  
negative.code:         Smax          = S_max
  
          ! S found with the dichotomy approach
          sigma_t_thin(i)  = dichotomy(k, Smin, Smax, eps, temperature(i), optical_depth)
  
        enddo
  
  