SLATEC Routines --- CHFIE ---

*DECK CHFIE
      REAL FUNCTION CHFIE (X1, X2, F1, F2, D1, D2, A, B)
C***BEGIN PROLOGUE  CHFIE
C***SUBSIDIARY
C***PURPOSE  Evaluates integral of a single cubic for PCHIA
C***LIBRARY   SLATEC (PCHIP)
C***TYPE      SINGLE PRECISION (CHFIE-S, DCHFIE-D)
C***AUTHOR  Fritsch, F. N., (LLNL)
C***DESCRIPTION
C
C          CHFIE:  Cubic Hermite Function Integral Evaluator.
C
C     Called by  PCHIA  to evaluate the integral of a single cubic (in
C     Hermite form) over an arbitrary interval (A,B).
C
C ----------------------------------------------------------------------
C
C  Calling sequence:
C
C        REAL  X1, X2, F1, F2, D1, D2, A, B
C        REAL  VALUE, CHFIE
C
C        VALUE = CHFIE (X1, X2, F1, F2, D1, D2, A, B)
C
C   Parameters:
C
C     VALUE -- (output) value of the requested integral.
C
C     X1,X2 -- (input) endpoints if interval of definition of cubic.
C
C     F1,F2 -- (input) function values at the ends of the interval.
C
C     D1,D2 -- (input) derivative values at the ends of the interval.
C
C     A,B -- (input) endpoints of interval of integration.
C
C***SEE ALSO  PCHIA
C***ROUTINES CALLED  (NONE)
C***REVISION HISTORY  (YYMMDD)
C   820730  DATE WRITTEN
C   820805  Converted to SLATEC library version.
C   870813  Minor cosmetic changes.
C   890411  1. Added SAVE statements (Vers. 3.2).
C           2. Added SIX to REAL declaration.
C   890411  REVISION DATE from Version 3.2
C   891214  Prologue converted to Version 4.0 format.  (BAB)
C   900315  CALLs to XERROR changed to CALLs to XERMSG.  (THJ)
C   900328  Added TYPE section.  (WRB)
C   910408  Updated AUTHOR section in prologue.  (WRB)
C   930503  Corrected to set VALUE=0 when IERR.ne.0.  (FNF)
C   930504  Eliminated IERR and changed name from CHFIV to CHFIE.  (FNF)
C***END PROLOGUE  CHFIE