c************************************************************************

      subroutine stalk_scat_int(ppol,mmech,mmech_c, sp_ave)

c************************************************************************

      complex h_stalk,sp_ave
      real pi,mpi
      integer pol,mech,mech_c
      integer ppol,mmech,mmech_c
      
      common /index/ pol,mech,mech_c

      external h_stalk

      pi=3.141592654
      mpi=-pi
      
      pol=ppol
      mech=mmech
      mech_c=mmech_c

      call integral1(h_stalk,mpi,pi,sp_ave)

      return

      end
      

c************************************************************************

      complex function h_stalk(phii)

c************************************************************************      

      complex g_stalk,result

      real amin,amax,z0min,z0max
      real phi_s,a_s,z0
      real phii
      real stalk_alpha_pdf
      
      external g_stalk
      
      common /stalk_limits/ amin,amax,z0min,z0max
      common /stalk_state/ phi_s,a_s,z0

      phi_s=phii

      call integral2(g_stalk,amin,amax, result)

      h_stalk=result*stalk_alpha_pdf(phi_s)


      return

      end

c************************************************************************

      complex function g_stalk(aa)

c************************************************************************

      complex stalk_scat


      real phi_s,a_s,z0
      real aa
      real stalk_a_pdf
      real z0_mn,z0_sig

      integer pol,mech,mech_c
      
      common /stalk_state/ phi_s,a_s,z0
      common /index/ pol,mech,mech_c
      common /z0_stat/ z0_mn,z0_sig
      
      a_s=aa
      z0=z0_mn


      g_stalk=stalk_scat(phi_s,a_s,z0,pol,mech,mech_c)
     &     *stalk_a_pdf(a_s)


      return
      end