SUBROUTINE SORT1(N,RA,RB)
*
*
*       Heapsort method (Press p. 231).
*       -------------------------------
*
      INTEGER  RB(N),RRB
      REAL*8  RA(N),RRA
*
*
      IF (N.LE.1) RETURN    ! bug fix Nov 2007.
      L = N/2+1
      IR=N
   10 CONTINUE
      IF (L.GT.1) THEN
	  L=L-1
	  RRA=RA(L)
	  RRB=RB(L)
      ELSE
          RRA=RA(IR)
	  RRB=RB(IR)
	  RA(IR)=RA(1)
	  RB(IR)=RB(1)
          IR=IR-1
	  IF (IR.EQ.1) THEN
	      RA(1)=RRA
	      RB(1)=RRB
	      RETURN
          END IF
      END IF
      I=L
      J=L+L
   20 IF (J.LE.IR) THEN
	  IF (J.LT.IR) THEN
	      IF (RA(J).LT.RA(J+1)) J=J+1
          END IF
	  IF (RRA.LT.RA(J)) THEN
	      RA(I)=RA(J)
	      RB(I)=RB(J)
	      I=J
	      J=J+J
          ELSE
	      J=IR+1
          END IF
          GO TO 20
      END IF
      RA(I)=RRA
      RB(I)=RRB
      GO TO 10
*
      END