poly, polyl

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Header File

math.h

Category

Math Routines

Prototype

double poly(double x, int degree, double coeffs[]);

long double polyl(long double x, int degree, long double coeffs[]);

Description

Generates a polynomial from arguments.

poly generates a polynomial in x, of degree degree, with coefficients coeffs[0], coeffs[1], ..., coeffs[degree]. For example, if n = 4, the generated polynomial is:

polyl is the long double version; it takes long double arguments and returns a long double result.

Return Value

poly and polyl return the value of the polynomial as evaluated for the given x.

Example

#include <stdio.h>
#include <math.h>
/* polynomial:  x**3 - 2x**2 + 5x - 1 */
int main(void)
{
  double array[] = { -1.0, 5.0, -2.0, 1.0
};
  double result;
  result = poly(2.0, 3, array);
  printf("The polynomial: x**3 - 2.0x**2 + 5x - 1 at 2.0 is %lf\n", result);
  return 0;
}

Portability

	POSIX	Win32	ANSI C	ANSI C++
poly		+
polyl		+