Restructured handling of tally reduction to make it more clear.

src/global.F90

@@ -180,7 +180,7 @@ module global
   integer :: MPI_BANK    ! MPI datatype for fission bank
 
   ! No reduction at end of batch
-  logical :: no_reduce = .false.
+  logical :: reduce_tallies = .true.
 
   ! ============================================================================
   ! TIMING VARIABLES

src/input_xml.F90

@@ -305,13 +305,13 @@ contains
 
     ! Check if the user has specified to not reduce tallies at the end of every
     ! batch
-    if (trim(no_reduce_) == 'on') no_reduce = .true.
+    if (trim(no_reduce_) == 'on') reduce_tallies = .false.
 
     ! Determine number of realizations
-    if (no_reduce) then
-       n_realizations = n_active * n_procs
-    else
+    if (reduce_tallies) then
        n_realizations = n_active
+    else
+       n_realizations = n_active * n_procs
     end if
        
 

src/intercycle.F90

@@ -390,7 +390,23 @@ contains
        ! =======================================================================
        ! ACTIVE BATCHES
 
-       if (no_reduce) then
+       if (reduce_tallies) then
+          ! In this case, global_tallies has already been reduced, so we don't
+          ! need to perform any more reductions and just take the values from
+          ! global_tallies directly
+
+          ! Define number of realizations
+          n = current_batch - n_inactive
+
+          ! Sample mean of keff
+          keff = global_tallies(K_ANALOG) % sum / n
+
+          if (n > 1) then
+             ! Standard deviation of the sample mean of k
+             keff_std = sqrt((global_tallies(K_ANALOG) % sum_sq/n - &
+                  keff*keff)/(n - 1))
+          end if
+       else
           ! In this case, no reduce was ever done on global_tallies. Thus, we
           ! need to reduce the values in sum and sum^2 to get the sample mean
           ! and its standard deviation
@@ -418,22 +434,6 @@ contains
              ! Standard deviation of the sample mean of k
              keff_std = sqrt((temp(2)/n - keff*keff)/(n - 1))
           end if
-       else
-          ! In this case, global_tallies has already been reduced, so we don't
-          ! need to perform any more reductions and just take the values from
-          ! global_tallies directly
-
-          ! Define number of realizations
-          n = current_batch - n_inactive
-
-          ! Sample mean of keff
-          keff = global_tallies(K_ANALOG) % sum / n
-
-          if (n > 1) then
-             ! Standard deviation of the sample mean of k
-             keff_std = sqrt((global_tallies(K_ANALOG) % sum_sq/n - &
-                  keff*keff)/(n - 1))
-          end if
        end if
 
     else

src/tally.F90

@@ -1309,26 +1309,25 @@ contains
     integer :: i   ! index in tallies array
 
 #ifdef MPI
-    if (.not. no_reduce) then
-       call reduce_tally_values()
-       if (.not. master) return
-    end if
+    if (reduce_tallies) call reduce_tally_values()
 #endif
 
-    ! Accumulate scores for each tally
-    do i = 1, n_tallies
-       call accumulate_score(tallies(i) % scores)
-    end do
+    if (master .or. (.not. reduce_tallies)) then
+       ! Accumulate scores for each tally
+       do i = 1, n_tallies
+          call accumulate_score(tallies(i) % scores)
+       end do
 
-    ! Before accumulating scores for global_tallies, we need to get the current
-    ! batch estimate of k_analog for displaying to output
-    k_batch = global_tallies(K_ANALOG) % value
+       ! Before accumulating scores for global_tallies, we need to get the
+       ! current batch estimate of k_analog for displaying to output
+       k_batch = global_tallies(K_ANALOG) % value
 
-    ! Accumulate scores for global tallies
-    call accumulate_score(global_tallies)
+       ! Accumulate scores for global tallies
+       call accumulate_score(global_tallies)
+    end if
 
 #ifdef MPI
-    if (no_reduce .and. current_batch == n_batches) &
+    if ((.not. reduce_tallies) .and. current_batch == n_batches) &
          call reduce_tally_sums()
 #endif
 
@@ -1401,15 +1400,13 @@ contains
 
     ! We also need to determine the total starting weight of particles from the
     ! last realization
-    if (.not. no_reduce) then
-       if (master) then
-          call MPI_REDUCE(MPI_IN_PLACE, total_weight, 1, MPI_REAL8, MPI_SUM, &
-               0, MPI_COMM_WORLD, mpi_err)
-       else
-          ! Receive buffer not significant at other processors
-          call MPI_REDUCE(total_weight, dummy, 1, MPI_REAL8, MPI_SUM, &
-               0, MPI_COMM_WORLD, mpi_err)
-       end if
+    if (master) then
+       call MPI_REDUCE(MPI_IN_PLACE, total_weight, 1, MPI_REAL8, MPI_SUM, &
+            0, MPI_COMM_WORLD, mpi_err)
+    else
+       ! Receive buffer not significant at other processors
+       call MPI_REDUCE(total_weight, dummy, 1, MPI_REAL8, MPI_SUM, &
+            0, MPI_COMM_WORLD, mpi_err)
     end if
 
   end subroutine reduce_tally_values
@@ -1417,10 +1414,10 @@ contains
 
 !===============================================================================
 ! REDUCE_TALLY_SUMS gathers data from the sum and sum_sq member variables of
-! TallyScores rather than the data from values. This is used if no_reduce is
-! turned on and scores are accumulated on every processor *before* being
-! reduced.
-!===============================================================================
+! TallyScores rather than the data from values. This is used if the user
+! specified that tallies should not be reduced and scores are accumulated on
+! every processor *before* being reduced.
+! ===============================================================================
 
 #ifdef MPI
   subroutine reduce_tally_sums()