C
C***********************************************************************
C                 COPYRIGHT ATLANTIC RICHFIELD COMPANY 1991            *
C***********************************************************************
CTITLESAUNWRP -- PHASE UNWRAP IN RADIANS                                00010001
CA    AUTHOR       B. S. BOK                                            00030001
CA    DESIGNER     B. S. BOK                                            00040001
CA    LANGUAGE     FORTRAN                                              00050001
CA    SYSTEM       IBM / CRAY                                           00060004
CA    WRITTEN      AUGUST, 1990                                         00070001
C     REVISED      12-21-91 JJC - MODIFIED TO MEET EDP STANDARDS.
C
CA                                                                      00150001
CA    CALL SAUNWRP (PHZ, LDIM)                                          00160004
CA                                                                      00180000
CA         IN/OUT  PHZ    = PHASE SPECTRUM                          R4  00190003
CA         INPUT   LDIM   = DIMENSION OF PHZ                        I4  00200003
CA                                                                      00350000
CA    THIS ROUTINE PERFORM THE PHASE UNWRAP IN RADIANS                  00360001
CA                                                                      00510000
C**************************************************************
C                                                             *
C SUBROUTINES AND FUNCTIONS CALLED FROM THIS ROUTINE          *
C                                                             *
C NO SUBROUTINES OR FUNCTIONS CALLED FROM THIS PROGRAM UNIT   *
C                                                             *
C**************************************************************
C
      SUBROUTINE SAUNWRP (PHZ,LDIM)
C
      IMPLICIT INTEGER (A-Z)
C
      DIMENSION PHZ(1)
C
      REAL     PHZ
      REAL     PI
      REAL     PI2
C
C
      PI = 3.141592654
      PI2 = PI * 2.
C
C---- FIRST POINT
C
      INT = IFIX ( PHZ(1) / PI )
      IF (INT .LT. 0) INT = (INT - 1 )  / 2
      IF (INT .GT. 0) INT = (INT + 1 )  / 2
      PHZ(1) = PHZ(1) - INT * PI2
      IF (LDIM .LE. 1) RETURN
C
C---- ALL OTHER POINTS
C
      DO 140 I = 2, LDIM
         INT = IFIX ( (PHZ(I) - PHZ(I - 1) )  / PI )
         IF (INT .GT. 0) GO TO 100
         IF (INT .EQ. 0) GO TO 120
         INT = (INT - 1 )  / 2
         PHZ(I) = PHZ(I) - INT * PI2
         GO TO 120
 100     CONTINUE
         INT = (INT + 1 )  / 2
         PHZ(I) = PHZ(I) - INT * PI2
 120     CONTINUE
 140  CONTINUE
C
      RETURN
      END