Improved efficiency of sort

MintonGroup · Oct 21, 2021 · 760fdde · 760fdde
1 parent ef402a5
commit 760fdde
Showing 1 changed file with 16 additions and 12 deletions.
diff --git a/src/util/util_sort.f90 b/src/util/util_sort.f90
@@ -74,8 +74,7 @@ module pure subroutine util_sort_dp(arr)
       do i = 2, n
          tmp = arr(i)
          j = i - 1
-         do while (j >= 1)
-            if (arr(j) <= tmp) exit
+         do while ((j >= 1) .and. (arr(j) > tmp))
             arr(j + 1) = arr(j)
             j = j - 1
          end do
@@ -109,11 +108,11 @@ module pure subroutine util_sort_index_dp(arr, ind)
       do i = 2, n
          itmp = ind(i)
          j = i - 1
-         do while (j >= 1)
-            if (arr(ind(j)) <= arr(itmp)) exit
+         do while ((j >= 2) .and. (arr(ind(j)) > itmp))
             ind(j + 1) = ind(j)
             j = j - 1
          end do
+         if ((j == 1) .and. (arr(ind(1)) > itmp)) ind(2) = ind(1)
          ind(j + 1) = itmp
       end do
 
@@ -138,8 +137,7 @@ module pure subroutine util_sort_i4b(arr)
       do i = 2, n
          tmp = arr(i)
          j = i - 1
-         do while (j >= 1)
-            if (arr(j) <= tmp) exit
+         do while ((j >= 1) .and. (arr(j) > tmp))
             arr(j + 1) = arr(j)
             j = j - 1
          end do
@@ -170,14 +168,21 @@ module pure subroutine util_sort_index_i4b(arr, ind)
          allocate(ind(n))
          ind = [(i, i=1, n)]
       end if
+
+      itmp = ind(2)
+      if (arr(ind(1)) > itmp) then
+         ind(2) = ind(1)
+         ind(1) = itmp
+      end if
+
       do i = 2, n
          itmp = ind(i)
          j = i - 1
-         do while (j >= 1)
-            if (arr(ind(j)) <= arr(itmp)) exit
+         do while ((j >= 2) .and. (arr(ind(j)) > itmp))
             ind(j + 1) = ind(j)
             j = j - 1
          end do
+         if ((j == 1) .and. (arr(ind(1)) > itmp)) ind(2) = ind(1)
          ind(j + 1) = itmp
       end do
 
@@ -202,8 +207,7 @@ module pure subroutine util_sort_sp(arr)
       do i = 2, n
          tmp = arr(i)
          j = i - 1
-         do while (j >= 1)
-            if (arr(j) <= tmp) exit
+         do while ((j >= 1) .and. (arr(j) > tmp))
             arr(j + 1) = arr(j)
             j = j - 1
          end do
@@ -237,11 +241,11 @@ module pure subroutine util_sort_index_sp(arr, ind)
       do i = 2, n
          itmp = ind(i)
          j = i - 1
-         do while (j >= 1)
-            if (arr(ind(j)) <= arr(itmp)) exit
+         do while ((j >= 2) .and. (arr(ind(j)) > itmp))
             ind(j + 1) = ind(j)
             j = j - 1
          end do
+         if ((j == 1) .and. (arr(ind(1)) > itmp)) ind(2) = ind(1)
          ind(j + 1) = itmp
       end do