anchor.diff:      !------------------------------------------------------------------------
       integer                                                :: i,j,k
   
  -    ! For Sigma
  -    real(kind = x_precision)                               :: Smin
  -    real(kind = x_precision)                               :: Smax
  -
  +    ! For variables
       real(kind = x_precision)                               :: f              ! Q+ - Q-
       real(kind = x_precision)                               :: tau_eff        ! Effective optical depth
       integer                                                :: optical_depth  ! Indicator for the optical thickness
  
positive.code: 
      write(*,*)'**** Critical Point',k,'********'
      write(*,*)'****************************************'
      write(*,"(' Optically thin (T,sigma) :',1p,E12.4,4x,1p,E12.4)")temp_c_thin,sigma_c_thin
      write(*,"(' Optically thick (T,sigma):',1p,E12.4,4x,1p,E12.4)")temp_c_thick,sigma_c_thick
      write(*,*)'****************************************'
  
    end subroutine display_critical_points
  
negative.code:         ! Optical thick case (tau >= 1)
          optical_depth = 1
  
          ! S found with the dichotomy approach
          sigma_t_thick(i) = dichotomy(k, S_min, S_max, eps, temperature(i), optical_depth)
  
          ! Optical thin case (tau < 1)
          optical_depth = 0
  
          ! S found with the dichotomy approach
          sigma_t_thin(i)  = dichotomy(k, S_min, S_max, eps, temperature(i), optical_depth)
  
        enddo
  
  