SUBROUTINE SORT_IDXD( N, IN, ASCEND, INDEX, STATUS ) *+ * Name: * SORT_IDXD * Purpose: * Create an index for a 1-dimensional DOUBLE PRECISION array * Language: * Starlink Fortran * Invocation: * CALL SORT_IDXD( N, IN, ASCEND, INDEX, STATUS ) * Description: * Creates an integer index or rank list for the input array IN. The * index lists the indices of the elements of IN in ascending or * descending order depending on the value of ASCEND. * Arguments: * N = INTEGER (given) * The number of data values to rank * IN = DOUBLE PRECISION[] (given) * The values to rank * ASCEND = LOGICAL (given) * Rank into ascending order? * INDEX = INTEGER[] (returned) * The ranking array * STATUS = INTEGER (given) * The global status. * Examples: * {routine_example_text} * {routine_example_description} * Pitfalls: * {pitfall_description}... * Notes: * {routine_notes}... * Prior Requirements: * {routine_prior_requirements}... * Side Effects: * {routine_side_effects}... * Algorithm: * {algorithm_description}... * Accuracy: * {routine_accuracy} * Timing: * {routine_timing} * External Routines Used: * {name_of_facility_or_package}: * {routine_used}... * Implementation Deficiencies: * {routine_deficiencies}... * References: * SORT Subroutine Guide : http://www.sr.bham.ac.uk/asterix-docs/Programmer/Guides/sort.html * Keywords: * package:sort, usage:public * Copyright: * Copyright (C) University of Birmingham, 1995 * Authors: * DJA: David J. Allan (Jet-X, University of Birmingham) * {enter_new_authors_here} * History: * 11 May 1993 (DJA): * Original version. * {enter_changes_here} * Bugs: * {note_any_bugs_here} *- * Type Definitions: IMPLICIT NONE ! No implicit typing * Global Constants: INCLUDE 'SAE_PAR' ! Standard SAE constants * Arguments Given: INTEGER N ! Number of names DOUBLE PRECISION IN(*) ! Input list data LOGICAL ASCEND ! Ascending order? * Arguments Returned: INTEGER INDEX(*) ! Output index * Status: INTEGER STATUS ! Global status * Local Variables: INTEGER I, J, L, IR ! Loop over list data INTEGER SWAP ! Index swap point *. * Check inherited global status. IF ( STATUS .NE. SAI__OK ) RETURN * Too few points? IF ( N .LT. 2 ) RETURN * Initialise L = N/2 + 1 IR = N * Loop forever DO WHILE ( .TRUE. ) IF ( L .GT. 1 ) THEN L = L - 1 SWAP = INDEX(L) ELSE SWAP = INDEX(IR) INDEX(IR) = INDEX(1) IR = IR - 1 IF ( IR .EQ. 1 ) THEN INDEX(1) = SWAP GOTO 50 END IF END IF I = L J = L + L IF ( ASCEND ) THEN DO WHILE ( J .LE. IR ) IF ( (J.LT.IR) .AND. : (IN(INDEX(J)).LT.IN(INDEX(J+1))) ) J = J + 1 IF ( IN(SWAP) .LT. IN(INDEX(J)) ) THEN INDEX(I) = INDEX(J) I = J J = J * 2 ELSE J = IR + 1 END IF END DO ELSE DO WHILE ( J .LE. IR ) IF ( (J.LT.IR) .AND. : (IN(INDEX(J)).GT.IN(INDEX(J+1))) ) J = J + 1 IF ( IN(SWAP) .GT. IN(INDEX(J)) ) THEN INDEX(I) = INDEX(J) I = J J = J * 2 ELSE J = IR + 1 END IF END DO END IF INDEX(I) = SWAP END DO 50 CONTINUE END