pvalue.f
SUBROUTINE PVALUE (L, NDER, X, YFIT, YP, A)
C***BEGIN PROLOGUE PVALUE
C***PURPOSE Use the coefficients generated by POLFIT to evaluate the
C polynomial fit of degree L, along with the first NDER of
C its derivatives, at a specified point.
C***LIBRARY SLATEC
C***CATEGORY K6
C***TYPE SINGLE PRECISION (PVALUE-S, DP1VLU-D)
C***KEYWORDS CURVE FITTING, LEAST SQUARES, POLYNOMIAL APPROXIMATION
C***AUTHOR Shampine, L. F., (SNLA)
C Davenport, S. M., (SNLA)
C***DESCRIPTION
C
C Written by L. F. Shampine and S. M. Davenport.
C
C Abstract
C
C The subroutine PVALUE uses the coefficients generated by POLFIT
C to evaluate the polynomial fit of degree L , along with the first
C NDER of its derivatives, at a specified point. Computationally
C stable recurrence relations are used to perform this task.
C
C The parameters for PVALUE are
C
C Input --
C L - the degree of polynomial to be evaluated. L may be
C any non-negative integer which is less than or equal
C to NDEG , the highest degree polynomial provided
C by POLFIT .
C NDER - the number of derivatives to be evaluated. NDER
C may be 0 or any positive value. If NDER is less
C than 0, it will be treated as 0.
C X - the argument at which the polynomial and its
C derivatives are to be evaluated.
C A - work and output array containing values from last
C call to POLFIT .
C
C Output --
C YFIT - value of the fitting polynomial of degree L at X
C YP - array containing the first through NDER derivatives
C of the polynomial of degree L . YP must be
C dimensioned at least NDER in the calling program.
C
C***REFERENCES L. F. Shampine, S. M. Davenport and R. E. Huddleston,
C Curve fitting by polynomials in one variable, Report
C SLA-74-0270, Sandia Laboratories, June 1974.
C***ROUTINES CALLED XERMSG
C***REVISION HISTORY (YYMMDD)
C 740601 DATE WRITTEN
C 890531 Changed all specific intrinsics to generic. (WRB)
C 890531 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 900510 Convert XERRWV calls to XERMSG calls. (RWC)
C 920501 Reformatted the REFERENCES section. (WRB)
C***END PROLOGUE PVALUE