powf

Power function

View other versions (4)

Contents

Interface
Description
Special Values
See Also
Standards
Page Comments

Interface

#include <math.h>double  pow (double x, double y)
long  powl (long double x, long double y)
float  powf (float x, float y)

#include <complex.h>double complex  cpow (double complex x, complex double y)
float complex  cpowf (float complex x, complex float y)
long double complex  cpowl (long double complex x, complex long double y)

Description

The pow functions compute x raised to the power of y, i.e.

$\mathrm{pow}(x,y) = x^y$

(2)

Example:

Example - Power function

Workings

#include <math.h>
#include <stdio.h>
int main(void)
{
  for(int i = 1; i < 5; i++)
     printf("pow(3.2, %d) = %lf\n", i, pow(3.2, i));  
  return 0;
}

Solution

Output:

pow(3.2, 1) = 3.200000
pow(3.2, 2) = 10.240000
pow(3.2, 3) = 32.768000
pow(3.2, 4) = 104.857600

Special Values

pow ( ±0, y ) returns ±∞ and raises the divide-by-zero floating-point exception for y an odd integer.

pow ( ±0, y ) returns +∞ and raises the divide-by-zero floating-point exception for y < 0 and not an odd integer.

pow ( ±0, y ) returns ±0 for y an odd integer > 0.

pow ( ±0, y ) returns +0 for y > 0 and not an odd integer.

pow ( -1, ±∞ ) returns 1.

pow ( 1, y ) returns 1 for any y, even a NaN.

pow ( x, ±0 ) returns 1 for any x, even a NaN.

pow ( x, y ) returns a NaN and raises the invalid floating-point exception for finite x < 0 and finite non-integer y.

pow ( x, -∞ ) returns +∞ for |x| < 1.

pow ( x, -∞ ) returns +0 for |x| > 1.

pow ( x, +∞ ) returns +0 for |x| < 1.

pow ( x, +∞ ) returns +∞ for |x| > 1.

pow ( -∞, y ) returns -0 for y an odd integer < 0.

pow ( -∞, y ) returns +0 for y < 0 and not an odd integer.

pow ( -∞, y ) returns -∞ for y an odd integer > 0.

pow ( -∞, y ) returns +∞ for y > 0 and not an odd integer.

pow ( +∞, y ) returns +0 for y < 0.

pow ( +∞, y ) returns +∞ for y > 0.

A domain error occurs if x is finite and negative and y is finite and not an integer.

A domain error can occur if x is 0 and y less than or equal to 0.

Standards

The pow function conforms to ISO/IEC 9899:1999(E).

double	`pow` (double x, double y)
long	`powl` (long double x, long double y)
float	`powf` (float x, float y)

double complex	`cpow` (double complex x, complex double y)
float complex	`cpowf` (float complex x, complex float y)
long double complex	`cpowl` (long double complex x, complex long double y)