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/* polevl.c
* p1evl.c
*
* Evaluate polynomial
*
*
*
* SYNOPSIS:
*
* int N;
* double x, y, coef[N+1], polevl[];
*
* y = polevl( x, coef, N );
*
*
*
* DESCRIPTION:
*
* Evaluates polynomial of degree N:
*
* 2 N
* y = C + C x + C x +...+ C x
* 0 1 2 N
*
* Coefficients are stored in reverse order:
*
* coef[0] = C , ..., coef[N] = C .
* N 0
*
* The function p1evl() assumes that coef[N] = 1.0 and is
* omitted from the array. Its calling arguments are
* otherwise the same as polevl().
*
*
* SPEED:
*
* In the interest of speed, there are no checks for out
* of bounds arithmetic. This routine is used by most of
* the functions in the library. Depending on available
* equipment features, the user may wish to rewrite the
* program in microcode or assembly language.
*
*/
/*
Cephes Math Library Release 2.1: December, 1988
Copyright 1984, 1987, 1988 by Stephen L. Moshier
Direct inquiries to 30 Frost Street, Cambridge, MA 02140
*/
double polevl (double x, double *coef, int N)
{
double ans;
int i;
double *p;
p = coef;
ans = *p++;
i = N;
do {
ans = ans * x + *p++;
} while (--i);
return ans;
}
/*
* Evaluate polynomial when coefficient of x is 1.0.
* Otherwise same as polevl.
*/
double p1evl (double x, double *coef, int N)
{
double ans;
double *p;
int i;
p = coef;
ans = x + *p++;
i = N-1;
do {
ans = ans * x + *p++;
} while (--i);
return ans;
}
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