Added ability to trace history of specific particle.

src/geometry.f90

@@ -231,7 +231,7 @@ contains
     type(Surface),  pointer :: surf => null()
 
     surf => surfaces(abs(p % surface))
-    if (verbosity >= 10) then
+    if (verbosity >= 10 .or. trace) then
        message = "    Crossing surface " // trim(int_to_str(surf % id))
        call write_message()
     end if
@@ -254,7 +254,7 @@ contains
        call score_surface_current(p)
 
        ! Display message
-       if (verbosity >= 10) then
+       if (verbosity >= 10 .or. trace) then
           message = "    Leaked out of surface " // trim(int_to_str(surf % id))
           call write_message()
        end if
@@ -373,7 +373,7 @@ contains
        p % last_xyz = p % coord0 % xyz + TINY_BIT * p % coord0 % uvw
 
        ! Diagnostic message
-       if (verbosity >= 10) then
+       if (verbosity >= 10 .or. trace) then
           message = "    Reflected from surface " // trim(int_to_str(surf%id))
           call write_message()
        end if
@@ -440,7 +440,7 @@ contains
 
     lat => lattices(p % coord % lattice)
 
-    if (verbosity >= 10) then
+    if (verbosity >= 10 .or. trace) then
        message = "    Crossing lattice " // int_to_str(lat % id)
        call write_message()
     end if

src/global.f90

@@ -168,6 +168,11 @@ module global
   ! screen and in logs
   integer :: verbosity = 7
 
+  ! Trace for single particle
+  logical    :: trace
+  integer    :: trace_cycle
+  integer(8) :: trace_particle
+
 contains
 
 !===============================================================================

src/input_xml.f90

@@ -136,6 +136,12 @@ contains
        weight_survive = cutoff_(1) % weight_avg
     end if
 
+    ! Particle trace
+    if (size(trace_) > 0) then
+       trace_cycle    = trace_(1)
+       trace_particle = trace_(2)
+    end if
+
   end subroutine read_settings_xml
 
 !===============================================================================

src/main.f90

@@ -90,6 +90,11 @@ contains
           ! set random number seed
           i_particle = (i_cycle-1)*n_particles + p % id
           call set_particle_seed(i_particle)
+          
+          ! set particle trace
+          trace = .false.
+          if (i_cycle == trace_cycle .and. &
+               p % id == trace_particle) trace = .true.
 
           ! transport particle
           call transport(p)

src/physics.f90

@@ -52,12 +52,12 @@ contains
        p % cell_born = p % coord % cell
     end if
 
-    if (verbosity >= 9) then
+    if (verbosity >= 9 .or. trace) then
        message = "Simulating Particle " // trim(int_to_str(p % id))
        call write_message()
     end if
 
-    if (verbosity >= 10) then
+    if (verbosity >= 10 .or. trace) then
        message = "    Born in cell " // trim(int_to_str(&
             cells(p % coord % cell) % id))
        call write_message()

src/xml-fortran/templates/settings_t.xml

@@ -25,5 +25,6 @@
   <variable name="survival_" tag="survival_biasing" type="word" length="3" />
   <variable name="cutoff_" tag="cutoff" type="cutoff_xml" dimension="1" />
   <variable name="cross_sections_" tag="cross_sections" type="word" length="255" />
+  <variable name="trace_" tag="trace" type="integer-array" />
 
 </template>