anchor.diff:    !-------------------------------------------------------------------------
     ! Subroutine in order to display the critical points
     !-------------------------------------------------------------------------
  -  subroutine display_critical_points(sigma_c_thin, temp_c_thin,sigma_c_thick, temp_c_thick,k)
  +  subroutine display_critical_points(sigma_c_thin, temp_c_thin, sigma_c_thick, temp_c_thick,k)
       implicit none
   
       real(kind = x_precision),intent(in) :: sigma_c_thin
  
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:   real(kind = x_precision) function dichotomy(k, S_min, S_max, eps, T, optical_depth)
      implicit none
  
      real(kind = x_precision),intent(in) :: S_min, S_max
      real(kind = x_precision),intent(in) :: eps
      real(kind = x_precision),intent(in) :: T
      integer,                 intent(in) :: k
      integer,                 intent(in) :: optical_depth
  
      integer                             :: j
      real(kind = x_precision)            :: tau_eff
      real(kind = x_precision)            :: Smin
      real(kind = x_precision)            :: Smax
      real(kind = x_precision)            :: f_min
      real(kind = x_precision)            :: f_max
      real(kind = x_precision)            :: f_center
      real(kind = x_precision)            :: S_center
  
      !-------------------------------------------------------------------------
      ! N-> Number of iterations for the dichotomy
  