!+
! Subroutine make_mat6_custom (ele, param, start_orb, end_orb, err_flag)
!
! Dummy routine for custom tracking. 
! This routine needs to be replaced for a custom calculation.
! If not replaced, and this routine is called, this routine will generate an error message.
!
! General rule: Your code may NOT modify any argument that is not listed as
! an output agument below."
!
! Input:
!   ele       -- Ele_struct: Element with transfer matrix
!   param     -- lat_param_struct: Parameters are needed for some elements.
!   start_orb -- Coord_struct: Coordinates at the beginning of element. 
!
! Output:
!   ele       -- Ele_struct: Element with transfer matrix.
!     %mat6     -- 6x6 transfer matrix.
!   end_orb   -- Coord_struct: Coordinates at the end of element.
!   err_flag  -- Logical: Set true if there is an error. False otherwise.
!+

subroutine make_mat6_custom (ele, param, start_orb, end_orb, err_flag)

use bmad_struct
use bmad_interface, except_dummy => make_mat6_custom

implicit none

type (ele_struct), target :: ele
type (coord_struct) :: start_orb, end_orb
type (lat_param_struct)  param

logical :: err_flag
character(32) :: r_name = 'make_mat6_custom'

!

call out_io (s_fatal$, r_name, 'THIS DUMMY ROUTINE SHOULD NOT HAVE BEEN CALLED IN THE FIRST PLACE.')
err_flag = .true.

end subroutine