SUBROUTINE INDEXX(N,ARRIN,INDX)
C     ===============================
C
C     Sorting routine
C
      INCLUDE 'IMPLIC.FOR'
      DIMENSION ARRIN(N),INDX(N)
      DO J=1,N
         INDX(J)=J
      END DO
      M=N/2+1
      IR=N
  10  CONTINUE
      IF(M.GT.1)THEN
         M=M-1
         INDXT=INDX(M)
         Q=ARRIN(INDXT)
       ELSE
         INDXT=INDX(IR)
         Q=ARRIN(INDXT)
         INDX(IR)=INDX(1)
         IR=IR-1
         IF(IR.EQ.1)THEN
            INDX(1)=INDXT
            RETURN
         END IF
      END IF
      I=M
      J=M+M
  20  IF(J.LE.IR)THEN
         IF(J.LT.IR)THEN
            IF(ARRIN(INDX(J)).LT.ARRIN(INDX(J+1)))J=J+1
         END IF
         IF(Q.LT.ARRIN(INDX(J))) THEN
            INDX(I)=INDX(J)
            I=J
            J=J+J
          ELSE
            J=IR+1
          ENDIF
        GO TO 20
        END IF
        INDX(I)=INDXT
      GO TO 10
      END