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/*--------------------------------------------------------------------------*
Name __poly - generates a polynomial from arguments
Usage double __poly ( double x, int n, const double* c );
Prototype in math.h
Description __poly generates a polynomial in x, of degree n, with
coefficients c[0], c[1], ..., c[n]. For example, if n=4,
the generated polynomial is
c[4]*x^4 + c[3]*x^3 + c[2]*x^2 + c[1]*x + c[0]
The polynomial is calculated using Horner's method:
polynom = (..((x*c[n] + c[n-1])*x + c[n-2])..)*x + c[0]
Return value __poly returns the value of the polynomial as evaluated for
the given x.
A range error occurs if the result exceeds double range.
*---------------------------------------------------------------------------*/
#include <stdio.h>
#include "dietlibm.h"
double __poly ( double x, size_t n, const double* c)
{
long double ret;
size_t i;
i = n;
c += n;
ret = 0;
do
ret = ret * x + *c--;
while ( i-- );
return ret;
}
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