*
* $Id: orthvc.F,v 1.1.1.1 1996/04/01 15:03:28 mclareni Exp $
*
* $Log: orthvc.F,v $
* Revision 1.1.1.1  1996/04/01 15:03:28  mclareni
* Mathlib gen
*
*
#include "gen/pilot.h"
      SUBROUTINE ORTHVC (N,NFREE,IFREE,X,FX,XLOW,XHI,Y,FY,P,SPMAX,SNMAX)
      INTEGER N, NFREE
      INTEGER IFREE(NFREE)
      DOUBLE PRECISION FX, FY, SPMAX, SNMAX
      DOUBLE PRECISION X(N), XLOW(N), XHI(N), Y(N), P(N)
      INTEGER I, II, KTEST, NFRM1, NTEMP
      LOGICAL EVEN
      DOUBLE PRECISION STPNEG, STPPOS
      KTEST=2*(NFREE/2)
      EVEN=.FALSE.
      IF(KTEST.EQ.NFREE) EVEN=.TRUE.
      NTEMP=NFREE
      IF(.NOT.EVEN) NTEMP=NFREE-1
      IF(NTEMP.GT.0) GOTO 10
      IF(FY.GT.FX) P(1)=-P(1)
      II=IFREE(1)
      CALL MXSTEP(Y(II),XLOW(II),XHI(II),P(1),SPMAX,SNMAX)
      RETURN
 10   SPMAX=1.0D+30
      SNMAX=1.0D+30
      DO 20 I=1,NTEMP,2
      II=IFREE(I)
      CALL MXSTEP(Y(II),XLOW(II),XHI(II),P(I),STPPOS,STPNEG)
      IF(STPPOS.LT.SPMAX) SPMAX=STPPOS
      IF(STPNEG.LT.SNMAX) SNMAX=STPNEG
      II=IFREE(I+1)
      P(I+1)=-P(I+1)
      CALL MXSTEP(Y(II),XLOW(II),XHI(II),P(I+1),STPPOS,STPNEG)
      IF(STPPOS.LT.SPMAX) SPMAX=STPPOS
      IF(STPNEG.LT.SNMAX) SNMAX=STPNEG
 20   CONTINUE
      IF(EVEN) RETURN
      NFRM1=NFREE-1
      P(NFRM1)=P(NFRM1)/2.0D+0
      P(NFREE)=-P(NFREE)/2.0D+0
      II=IFREE(NFREE)
      CALL MXSTEP(Y(II),XLOW(II),XHI(II),P(NFREE),STPPOS,STPNEG)
      IF(STPPOS.LT.SPMAX) SPMAX=STPPOS
      IF(STPNEG.LT.SNMAX) SNMAX=STPNEG
      RETURN
      END