PVALUE(3)

SYNOPSIS
SUBROUTINE PVALUE (L, NDER, X, YFIT, YP, A)

NAME
pvalue - Use the coefficients generated by POLFIT to evaluate the polynomial fit of degree L, along with the first NDER of its derivatives, at a specified point.

LIBRARY
SLATEC

CATEGORY
K6

TYPE
SINGLE PRECISION (PVALUE-S, DP1VLU-D)

KEYWORDS
CURVE FITTING, LEAST SQUARES, POLYNOMIAL APPROXIMATION

AUTHOR
Shampine, L. F., (SNLA) Davenport, S. M., (SNLA)

DESCRIPTION
Written by L. F. Shampine and S. M. Davenport. Abstract The subroutine PVALUE uses the coefficients generated by POLFIT to evaluate the polynomial fit of degree L , along with the first NDER of its derivatives, at a specified point. Computationally stable recurrence relations are used to perform this task. The parameters for PVALUE are Input -- L - the degree of polynomial to be evaluated. L may be any non-negative integer which is less than or equal to NDEG , the highest degree polynomial provided by POLFIT . NDER - the number of derivatives to be evaluated. NDER may be 0 or any positive value. If NDER is less than 0, it will be treated as 0. X - the argument at which the polynomial and its derivatives are to be evaluated. A - work and output array containing values from last call to POLFIT . Output -- YFIT - value of the fitting polynomial of degree L at X YP - array containing the first through NDER derivatives of the polynomial of degree L . YP must be dimensioned at least NDER in the calling program.

REFERENCES
L. F. Shampine, S. M. Davenport and R. E. Huddleston, Curve fitting by polynomials in one variable, Report SLA-74-0270, Sandia Laboratories, June 1974.

ROUTINES CALLED
XERMSG

REVISION HISTORY (YYMMDD)
740601 DATE WRITTEN
890531 Changed all specific intrinsics to generic. (WRB)
890531 REVISION DATE from Version 3.2
891214 Prologue converted to Version 4.0 format. (BAB)
900315 CALLs to XERROR changed to CALLs to XERMSG. (THJ)
900510 Convert XERRWV calls to XERMSG calls. (RWC)
920501 Reformatted the REFERENCES section. (WRB)