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/* simpsn.c */
/* simpsn.c
* Numerical integration of function tabulated
* at equally spaced arguments
*/
/* Coefficients for Cote integration formulas */
/* Note: these numbers were computed using 40-decimal precision. */
#define NCOTE 8
/* 6th order formula */
/*
* static double simcon[] =
* {
* 4.88095238095238095E-2,
* 2.57142857142857142857E-1,
* 3.2142857142857142857E-2,
* 3.2380952380952380952E-1,
* };
*/
/* 8th order formula */
static double simcon[] = {
3.488536155202821869E-2,
2.076895943562610229E-1,
-3.27336860670194003527E-2,
3.7022927689594356261E-1,
-1.6014109347442680776E-1,
};
/* 10th order formula */
/*
* static double simcon[] =
* {
* 2.68341483619261397039E-2,
* 1.77535941424830313719E-1,
* -8.1043570626903960237E-2,
* 4.5494628827962161295E-1,
* -4.3515512265512265512E-1,
* 7.1376463043129709796E-1,
* };
*/
/* simpsn.c 2 */
/* 20th order formula */
/*
* static double simcon[] =
* {
* 1.182527324903160319E-2,
* 1.14137717644606974987E-1,
* -2.36478370511426964E-1,
* 1.20618689348187566E+0,
* -3.7710317267153304677E+0,
* 1.03367982199398011435E+1,
* -2.270881584397951229796E+1,
* 4.1828057422193554603E+1,
* -6.4075279490154004651555E+1,
* 8.279728347247285172085E+1,
* -9.0005367135242894657916E+1,
* };
*/
/* simpsn.c 3 */
double simpsn(double[], double);
double simpsn(f, delta)
double f[]; /* tabulated function */
double delta; /* spacing of arguments */
{
extern double simcon[];
double ans;
int i;
ans = simcon[NCOTE / 2] * f[NCOTE / 2];
for (i = 0; i < NCOTE / 2; i++)
ans += simcon[i] * (f[i] + f[NCOTE - i]);
return (ans * delta * NCOTE);
}
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