!
!  In the calling program define the structure by:
!      RECORD / PC_STRUCT /PC
!
!  Example values
!
! PC.CROSS(n).Z          z-coordinate of n'th parasitic crossing
! PC.BEAM_BEAM(m,n)  logical: true if beam bunch m has close
!                                    encounter with beam bunch n
! PC.CROSS(n).ORBIT       orbit of beam at n
! PC.CROSS(n).ELE.X.BETA
! PC.CROSS(n).ELE.X.SIGMA
! PC.CROSS(n).DNUV       vertical long range tune shift at n
! PC.CROSS(n).DNUV_X       vertical long range tune shift at n (horiz sep only)
! PC.CROSS(n).DNUV_Y       vertical long range tune shift at n (vert sep only)
! PC.CROSS(n).IX         parasitic crossing n is in lat element ix
! PC.CROSS(n).MAT6(6,6)  matrix to propogate from end of element ix
! PC.TOTAL_PC             number of parasitic crossings
! PC.POSBUNCH_ELEBUNCH(p,q,r) parsitic crossing where bunch p positron and
!                                 bunch q electron miss ,rth time (r=1,2)
!-

 ! Structure definitions

module bunchcross_mod

  use bmad
  use bmadz_mod

  type pc_cross_struct
    real(rp) dnuv, dnuh, dnuv_x, dnuh_x, dnuv_y, dnuh_y, b_param, distance_to_bpm
    type (ele_struct)  ele
    type (coord_struct)  orbit
    integer ix
    character*16 bpm
  end type

  type pc_struct
     type (pc_cross_struct)  cross(100)!cross(1000)
     integer posbunch_elebunch(100,100,2) !posbunch_elebunch(100,100,2)
    integer total_pc                 ! number of parasitic crossings
    logical beam_beam(100,100) !beam_beam(100,1000)
    logical Pos_beam_beam(100,100) !Pos_beam_beam(100,1000)
    logical Ele_beam_beam(100,100) !Ele_beam_beam(100,1000)
  end type

contains

!........................................................................
!
! Subroutine : TRACK_TO_PC (CO, PARAM, PC)
!
! Description: Subroutine to track from end of element that includes 
!              parasitic crossing to crossing point
!
! Arguments  :
!    Input:  PC
!            CO(:)  closed orbit at end of each lat element
!    Output:
!            PC   -- PC_STRUCT: pc.cross(j).orbit  orbit at parasitic 
!                    crossing point          
!
! Mod/Commons:    
!
! Calls      :      
!
! Author     : 
!
! Modified   :     
!             
!........................................................................
!
!
! $Log$
! Revision 1.7  2007/01/30 16:15:14  dcs
! merged with branch_bmad_1.
!
! Revision 1.3  2004/08/26 21:54:01  dlr
! error message if element name in constraint file is not in lat
!
! Revision 1.2  2003/08/12 01:46:04  mjf7
! Fixed some parameter inconsistencies and added four more subroutines to modules.      - mjf
!
! Revision 1.2  2003/04/30 17:14:56  cesrulib
! dlr's changes since last import
!
! Revision 1.1.1.1  2002/12/13 19:23:30  cesrulib
! import bmadz
!
!
!........................................................................
!


subroutine track_to_pc(co, param, PC, lat)

  implicit none

  type (lat_struct) lat
  type (lat_param_struct)  param
  type (coord_struct), allocatable ::  co(:)
  type (pc_struct) pc

  integer i,j
  integer iy_before, iy_after, k
  
  real(rp) xafter, xbefore
!

  do j=1,pc%total_pc
    i=pc%cross(j)%ix
    call track1 (co(i-1), pc%cross(j)%ele, param, pc%cross(j)%orbit)
    k=i
    xbefore=99.
    xafter = 99.
    do while (index(lat%ele(k)%name,'DET') == 0)
      if(k==0)exit
      k=k-1
!      print '(a16,2i10,5x,a16)','before', i,k, lat%ele(k)%name
    end do
    iy_before = k
    xbefore = pc%cross(j)%ele%s-lat%ele(k)%s 
    k=i
    do while (index(lat%ele(k)%name,'DET') == 0)
     k=k+1
!      print '(a16,2i10,5x,a16)','after', i,k, lat%ele(k)%name
    end do
    iy_after = k
    xafter = lat%ele(k)%s-pc%cross(j)%ele%s 
!    print '(a,2f12.4)','xafter,xbefore', xafter, xbefore
    if(xafter > xbefore)then
      pc%cross(j)%distance_to_bpm = xbefore
      pc%cross(j)%bpm = lat%ele(iy_before)%name
    else
      pc%cross(j)%distance_to_bpm = xafter
      pc%cross(j)%bpm = lat%ele(iy_after)%name
    endif
!   pause
  enddo




  return
end subroutine track_to_pc

!........................................................................
!
! Subroutine : TWISS_TO_PC ( LAT, global, PC)
!
! Description: Subroutine to propagate twiss parameters from end of element 
!              that includes parasitic crossing to crossing point and compute
!              beam size
!
! Arguments  :    
!    Input:  LAT, GLOBAL
!
!    Output:
!       PC   -- PC_STRUCT: pc.cross(j).ele  twiss at parasitic crossing point
!                        pc.cross(j).sigma  beam size at parasitic crossing
!
! Mod/Commons:    
!
! Calls      :      
!
! Author     : 
!
! Modified   :     
!             
!........................................................................
!
!
! $Log$
! Revision 1.7  2007/01/30 16:15:14  dcs
! merged with branch_bmad_1.
!
! Revision 1.3  2004/08/26 21:54:01  dlr
! error message if element name in constraint file is not in lat
!
! Revision 1.2  2003/08/12 01:46:04  mjf7
! Fixed some parameter inconsistencies and added four more subroutines to modules.      - mjf
!
! Revision 1.2  2003/04/30 17:14:56  cesrulib
! dlr's changes since last import
!
! Revision 1.1.1.1  2002/12/13 19:23:30  cesrulib
! import bmadz
!
!
!........................................................................
!


subroutine twiss_to_pc(lat, global, PC)

  implicit none

  type (lat_struct)  lat
  type (pc_struct) pc
  type (global_struct)  global
  real(rp) betax, etax
  integer i,j
!
  do j=1,pc%total_pc
    i=pc%cross(j)%ix
    call twiss_propagate1 (lat%ele(i-1), pc%cross(j)%ele)
    betax = pc%cross(j)%ele%a%beta
    etax = pc%cross(j)%ele%a%eta
    pc%cross(j)%ele%a%sigma =  sqrt(max(0.0, &
                 global%wig%x_emit*betax + (global%wig%sige_e*etax)**2))
  enddo

  return
end subroutine twiss_to_pc



end module bunchcross_mod