DCSEVL(3)

SYNOPSIS
DOUBLE PRECISION FUNCTION DCSEVL (X, CS, N)

NAME
dcsevl - Evaluate a Chebyshev series.

LIBRARY
SLATEC (FNLIB)

CATEGORY
C3A2

TYPE
DOUBLE PRECISION (CSEVL-S, DCSEVL-D)

KEYWORDS
CHEBYSHEV SERIES, FNLIB, SPECIAL FUNCTIONS

AUTHOR
Fullerton, W., (LANL)

DESCRIPTION
Evaluate the N-term Chebyshev series CS at X. Adapted from a method presented in the paper by Broucke referenced below. Input Arguments -- X value at which the series is to be evaluated. CS array of N terms of a Chebyshev series. In evaluating CS, only half the first coefficient is summed. N number of terms in array CS.

REFERENCES
R. Broucke, Ten subroutines for the manipulation of Chebyshev series, Algorithm 446, Communications of the A.C.M. 16, (1973) pp. 254-256. L. Fox and I. B. Parker, Chebyshev Polynomials in Numerical Analysis, Oxford University Press, 1968, page 56.

ROUTINES CALLED
D1MACH, XERMSG

REVISION HISTORY (YYMMDD)
770401 DATE WRITTEN
890831 Modified array declarations. (WRB)
890831 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)
900329 Prologued revised extensively and code rewritten to allow X to be slightly outside interval (-1,+1). (WRB)
920501 Reformatted the REFERENCES section. (WRB)