anchor.diff:  
       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(*,"(' 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
  
positive.code:   real(kind = x_precision) function dichotomy(k, S_min, S_max, eps, T, optical_depth)
      implicit none
  
      real(kind = x_precision),intent(inout) :: 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
  
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
  
  