 
      INTEGER FUNCTION CHFMC(D1,D2,DELTA)
C***BEGIN PROLOGUE  CHFMC
C***REFER TO  PCHMC
C***ROUTINES CALLED  R1MACH
C***REVISION DATE  870707   (YYMMDD)
C***DESCRIPTION
C
C          CHFMC:  Cubic Hermite Function Monotonicity Checker.
C
C    Called by  PCHMC  to determine the monotonicity properties of the
C    cubic with boundary derivative values D1,D2 and chord slope DELTA.
C
C ----------------------------------------------------------------------
C
C  Calling sequence:
C
C        REAL  D1, D2, DELTA
C        INTEGER  ISMON, CHFMC
C
C        ISMON = CHFMC (D1, D2, DELTA)
C
C   Parameters:
C
C     D1,D2 -- (input) derivative values at the ends of an interval.
C
C     DELTA -- (input) data slope over that interval.
C
C     ISMON -- (output) integer function value, indicating the monoto-
C           nicity of the cubic segment:
C             ISMON = -1  if function is strictly decreasing;
C             ISMON =  0  if function is constant;
C             ISMON =  1  if function is strictly increasing;
C             ISMON =  2  if function is non-monotonic;
C             ISMON =  3  if unable to determine.
C
C  Fortran intrinsics used:  SIGN.
C  Other routines used:  R1MACH.
C
C***END PROLOGUE  CHFMC
 
 
