Sorting algorithms/Gnome sort: Difference between revisions

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 end subroutine Gnomesort
+Optimized Version
+      SUBROUTINE OPTIMIZEDGNOMESORT(A)     ! Nice
+      IMPLICIT NONE
+!
+! Dummy arguments
+!
+      REAL , DIMENSION(0:)  ::  A
+      INTENT (INOUT) A
+!
+! Local variables
+!
+      INTEGER  ::  posy
+!
+      DO posy = 1 , UBOUND(A , 1)       !size(a)-1
+         CALL GNOMESORT(A , posy)
+      END DO
+      RETURN
+      CONTAINS
+      SUBROUTINE GNOMESORT(A , Upperbound)
+      IMPLICIT NONE
+!
+! Dummy arguments
+!
+      INTEGER  ::  Upperbound
+      REAL , DIMENSION(0:)  ::  A
+      INTENT (IN) Upperbound
+      INTENT (INOUT) A
+!
+! Local variables
+!
+      LOGICAL  ::  eval
+      INTEGER  ::  posy
+      REAL  ::  t
+!
+      eval = .FALSE.
+      posy = Upperbound
+      eval = (posy>0) .AND. (A(posy - 1)>A(posy))
+!     do while ((posy > 0) .and. (a(posy-1) > a(posy)))
+      DO WHILE ( eval )
+         t = A(posy)
+         A(posy) = A(posy - 1)
+         A(posy - 1) = t
+!
+         posy = posy - 1
+         eval = (posy>0)
+         IF( eval )THEN     ! Have to use as a guard condition
+            eval = (A(posy - 1)>A(posy))
+         ELSE
+            eval = .FALSE.
+         END IF
+      END DO
+      RETURN
+      END SUBROUTINE GNOMESORT
+      END SUBROUTINE OPTIMIZEDGNOMESORT
+!
 end program example</lang>