anchor.diff:         &               n_inter_max_warn, &
          &               n_reabs_max,  &
          &               n_reabs_max_warn,  &
  +       &               forced_first_interaction, &
  +       &               forced_first_interaction_algorithm, &
          &               kill_on_scatter, &
          &               monochromatic_energy_threshold
   
  
positive.code: 
    end subroutine do_final_mono
  
    subroutine propagate(p, peeloff_scattering_only)
  
      implicit none
  
      type(photon), intent(inout) :: p
      logical,intent(in) :: peeloff_scattering_only
      integer(idp) :: interactions
      real(dp) :: tau_achieved, tau, tau_escape
      type(photon) :: p_tmp
  
negative.code:                 end if
  
                  ! Propagate until photon is absorbed again
                  call propagate(p)
  
               end do
  
  