SLATEC Routines --- PCHCE ---

*DECK PCHCE
      SUBROUTINE PCHCE (IC, VC, N, X, H, SLOPE, D, INCFD, IERR)
C***BEGIN PROLOGUE  PCHCE
C***SUBSIDIARY
C***PURPOSE  Set boundary conditions for PCHIC
C***LIBRARY   SLATEC (PCHIP)
C***TYPE      SINGLE PRECISION (PCHCE-S, DPCHCE-D)
C***AUTHOR  Fritsch, F. N., (LLNL)
C***DESCRIPTION
C
C          PCHCE:  PCHIC End Derivative Setter.
C
C    Called by PCHIC to set end derivatives as requested by the user.
C    It must be called after interior derivative values have been set.
C                      -----
C
C    To facilitate two-dimensional applications, includes an increment
C    between successive values of the D-array.
C
C ----------------------------------------------------------------------
C
C  Calling sequence:
C
C        PARAMETER  (INCFD = ...)
C        INTEGER  IC(2), N, IERR
C        REAL  VC(2), X(N), H(N), SLOPE(N), D(INCFD,N)
C
C        CALL  PCHCE (IC, VC, N, X, H, SLOPE, D, INCFD, IERR)
C
C   Parameters:
C
C     IC -- (input) integer array of length 2 specifying desired
C           boundary conditions:
C           IC(1) = IBEG, desired condition at beginning of data.
C           IC(2) = IEND, desired condition at end of data.
C           ( see prologue to PCHIC for details. )
C
C     VC -- (input) real array of length 2 specifying desired boundary
C           values.  VC(1) need be set only if IC(1) = 2 or 3 .
C                    VC(2) need be set only if IC(2) = 2 or 3 .
C
C     N -- (input) number of data points.  (assumes N.GE.2)
C
C     X -- (input) real array of independent variable values.  (the
C           elements of X are assumed to be strictly increasing.)
C
C     H -- (input) real array of interval lengths.
C     SLOPE -- (input) real array of data slopes.
C           If the data are (X(I),Y(I)), I=1(1)N, then these inputs are:
C                  H(I) =  X(I+1)-X(I),
C              SLOPE(I) = (Y(I+1)-Y(I))/H(I),  I=1(1)N-1.
C
C     D -- (input) real array of derivative values at the data points.
C           The value corresponding to X(I) must be stored in
C                D(1+(I-1)*INCFD),  I=1(1)N.
C          (output) the value of D at X(1) and/or X(N) is changed, if
C           necessary, to produce the requested boundary conditions.
C           no other entries in D are changed.
C
C     INCFD -- (input) increment between successive values in D.
C           This argument is provided primarily for 2-D applications.
C
C     IERR -- (output) error flag.
C           Normal return:
C              IERR = 0  (no errors).
C           Warning errors:
C              IERR = 1  if IBEG.LT.0 and D(1) had to be adjusted for
C                        monotonicity.
C              IERR = 2  if IEND.LT.0 and D(1+(N-1)*INCFD) had to be
C                        adjusted for monotonicity.
C              IERR = 3  if both of the above are true.
C
C    -------
C    WARNING:  This routine does no validity-checking of arguments.
C    -------
C
C  Fortran intrinsics used:  ABS.
C
C***SEE ALSO  PCHIC
C***ROUTINES CALLED  PCHDF, PCHST, XERMSG
C***REVISION HISTORY  (YYMMDD)
C   820218  DATE WRITTEN
C   820805  Converted to SLATEC library version.
C   870707  Minor corrections made to prologue..
C   890411  Added SAVE statements (Vers. 3.2).
C   890531  Changed all specific intrinsics to generic.  (WRB)
C   890831  Modified array declarations.  (WRB)
C   890831  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  Improved purpose.  (FNF)
C***END PROLOGUE  PCHCE