Fix for dynamic_aperture when using LTT tracking. (#1223)

bsim/dynamic_aperture/dynamic_aperture.f90

@@ -28,6 +28,7 @@ program dynamic_aperture_program
 type (branch_struct), pointer :: branch
 
 procedure(track_many_hook_def) :: track_many_hook
+procedure(lat_make_mat6_hook_def) :: lat_make_mat6_hook
 
 real(rp) dpz(20), pz(20), vec(6)
 real(rp) :: ramping_start_time = 0
@@ -43,10 +44,10 @@ program dynamic_aperture_program
 
 !
 
-track1_preprocess_ptr => ltt_track1_preprocess
-track1_bunch_hook_ptr => ltt_track1_bunch_hook
-track_many_hook_ptr   => track_many_hook
-
+track1_preprocess_ptr   => ltt_track1_preprocess
+track1_bunch_hook_ptr   => ltt_track1_bunch_hook
+track_many_hook_ptr     => track_many_hook
+lat_make_mat6_hook_ptr  => lat_make_mat6_hook
 ! Set inits
 
 bmad_com%auto_bookkeeper = .false.   ! Makes tracking faster

bsim/dynamic_aperture/lat_make_mat6_hook.f90

@@ -0,0 +1,78 @@
+!+
+! Subroutine lat_make_mat6_hook (finished, lat, ix_ele, ref_orb, ix_branch, err_flag)
+!
+! Prototype routine that can be customized for constructing element transfer matrices.
+!
+! Subroutine to make the first order transfer map for an element or elements:
+!   r_out = M * r_in + vec0
+! M is the 6x6 linear transfer matrix (Jacobian) about the 
+! reference orbit ref_orb.
+!
+! If the element lat%ele(ix_ele) is a lord element then the martices of 
+! all the slave elements will be recomputed.
+!
+! Input:
+!   lat         -- lat_struct: Lat containing the elements.
+!   ix_ele      -- Integer, optional: Index of the element. If not present
+!                    or negative, the matrices for all elements will be calculated.
+!   ref_orb(0:) -- Coord_struct, optional: Coordinates of the reference orbit
+!                   around which the matrix is calculated. If not present 
+!                   then the referemce is taken to be the origin.
+!   ix_branch   -- Integer, optional: Branch index. Default is 0 (main lattice).
+!                   -1 => All branches/all elements (ref_orb & ix_ele will be ignored).
+!
+! Output:
+!   finished    -- logical: When set True, the standard lat_make_mat6 code will not be called.
+!   lat         -- lat_struct:
+!     ele(:)%mat6  -- Real(rp): 1st order (Jacobian) 6x6 transfer matrix.
+!     ele(:)%vec0  -- Real(rp): 0th order transfer vector.
+!   err_flag    -- Logical, optional: True if there is an error. False otherwise.
+!-
+
+recursive subroutine lat_make_mat6_hook (finished, lat, ix_ele, ref_orb, ix_branch, err_flag)
+
+use da_program_mod
+
+implicit none
+
+type (lat_struct), target :: lat
+type (coord_struct), optional :: ref_orb(0:)
+type (coord_struct), allocatable :: orbit(:)
+type (branch_struct), pointer :: branch
+type (ltt_params_struct), pointer :: lttp
+type (ltt_com_struct), pointer :: ltt_com
+
+real(rp), pointer :: mat6(:,:), vec0(:)
+
+integer, optional :: ix_ele, ix_branch
+integer state, n
+
+logical, optional :: err_flag
+logical finished
+
+character(*), parameter :: r_name = 'lat_make_mat6_hook'
+
+!
+
+branch => lat%branch(integer_option(0, ix_branch))
+finished = .false.
+
+branch => lat%branch(ix_branch)
+lttp => ltt_params_global
+ltt_com => ltt_com_global
+
+! Normal Bmad tracking?
+
+finished = .false.
+if (lttp%tracking_method == 'OLD' .or. ltt_com%track_bypass) return
+
+! This is to get around the problem that the other tracking_methods will not calculate ref_orb so
+! approximate the ref_orb by normal tracking 
+
+call reallocate_coord (orbit, lat, ix_branch)
+orbit(0) = ref_orb(0)
+call track_all(lat, orbit, ix_branch, state, err_flag)
+n = branch%n_ele_max
+ref_orb(1:n) = orbit(1:n)
+
+end subroutine

bsim/dynamic_aperture/track_many_hook.f90

@@ -58,7 +58,7 @@ subroutine track_many_hook (finished, lat, orbit, ix_start, ix_end, direction, i
 ! Normal Bmad tracking?
 
 finished = .false.
-if (ltt_params_global%tracking_method == 'OLD' .or. ltt_com%track_bypass) return
+if (lttp%tracking_method == 'OLD' .or. ltt_com%track_bypass) return
 finished = .true.
 
 !

tao/version/tao_version_mod.f90

@@ -6,5 +6,5 @@
 !-
 
 module tao_version_mod
-character(*), parameter :: tao_version_date = "2024/10/08 06:37:36"
+character(*), parameter :: tao_version_date = "2024/10/08 16:23:17"
 end module