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/* dcsevl.f -- translated by f2c (version 20041007).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
or, if you install libf2c.a in a standard place, with -lf2c -lm
-- in that order, at the end of the command line, as in
cc *.o -lf2c -lm
Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
http://www.netlib.org/f2c/libf2c.zip
*/
/** This routine has been editted to be thread safe **/
#define V3P_NETLIB_SRC
#include "v3p_netlib.h"
/* Table of constant values */
static integer c__4 = 4;
static integer c__2 = 2;
static integer c__3 = 3;
static integer c__1 = 1;
/* DECK DCSEVL */
doublereal dcsevl_(doublereal *x, doublereal *cs, integer *n)
{
/* Initialized data */
// static logical first = TRUE_;
/* System generated locals */
integer i__1;
doublereal ret_val;
/* Local variables */
integer i__;
doublereal b0, b1, b2;
integer ni;
doublereal twox;
/* static */ doublereal onepl;
extern doublereal d1mach_(integer *);
extern /* Subroutine */ int xermsg_(char *, char *, char *, integer *,
integer *, ftnlen, ftnlen, ftnlen);
/* ***BEGIN PROLOGUE DCSEVL */
/* ***PURPOSE 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) */
/* ***END PROLOGUE DCSEVL */
/* Parameter adjustments */
--cs;
/* Function Body */
/* ***FIRST EXECUTABLE STATEMENT DCSEVL */
// d1mach has been made thread safe, so there is no need for the
// statics in determining these values
// if (first) {
// onepl = 1. + d1mach_(&c__4);
// }
// first = FALSE_;
onepl = 1. + d1mach_(&c__4);
if (*n < 1) {
xermsg_("SLATEC", "DCSEVL", "NUMBER OF TERMS .LE. 0", &c__2, &c__2, (
ftnlen)6, (ftnlen)6, (ftnlen)22);
}
if (*n > 1000) {
xermsg_("SLATEC", "DCSEVL", "NUMBER OF TERMS .GT. 1000", &c__3, &c__2,
(ftnlen)6, (ftnlen)6, (ftnlen)25);
}
if (abs(*x) > onepl) {
xermsg_("SLATEC", "DCSEVL", "X OUTSIDE THE INTERVAL (-1,+1)", &c__1, &
c__1, (ftnlen)6, (ftnlen)6, (ftnlen)30);
}
b2 = 0.;
b1 = 0.;
b0 = 0.;
twox = *x * 2.;
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
b2 = b1;
b1 = b0;
ni = *n + 1 - i__;
b0 = twox * b1 - b2 + cs[ni];
/* L10: */
}
ret_val = (b0 - b2) * .5;
return ret_val;
} /* dcsevl_ */
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