pow(), powf(), powl() — Raise to power

Standards

Standards / Extensions C or C++ Dependencies
ISO C
POSIX.1
XPG4
XPG4.2
ISO/ANSI C++
C99
Single UNIX Specification, Version 3
C++ TR1 C99
 both  

Format

#include <math.h>

double pow(double x, double y);
double pow(double x, int y);                    /* C++ only */
float pow(float x, int y);                      /* C++ only */
float pow(float x, float y);                    /* C++ only */
long double pow(long double x, int y);          /* C++ only */
long double pow(long double x, long double y);  /* C++ only */
float powf(float x, float y);
long double powl(long double x, long double y);

General description

The pow(), powf(), and powl() functions calculate the value of x to the power of y.
Note: These functions work in both IEEE Binary Floating-Point and hexadecimal floating-point formats. See IEEE binary floating-point for more information about IEEE Binary Floating-Point.
Restriction: The powf() function does not support the _FP_MODE_VARIABLE feature test macro.

Returned value

If successful, the pow(), powf(), and powl() functions return the value of x to the power of y.

If y is 0, the function returns 1.

If x is negative and y is non-integral, the function sets errno to EDOM and returns -HUGE_VAL. If the correct value is outside the range of representable values, ±HUGE_VAL is returned according to the sign of the value, and the value of ERANGE is stored in errno.

Special behavior for IEEE: If x is negative or 0, then the y parameter must be an integer. If y is 0, the function returns 1.0 for all x parameters.

If an overflow occurs, the function returns HUGE_VAL and sets errno to ERANGE.

If both x and y are negative, the function returns NaNQ and sets errno to EDOM.

If x is 0 and y is negative, the function returns HUGE_VAL and does not modify errno, but powf sets errno to ERANGE.
Note: When environment variable _EDC_SUSV3 is set to 2, and if x is 0 and y is negative, the function returns -HUGE_VAL and sets errno to ERANGE.

Example

CELEBP05 
/* CELEBP05

   This example calculates the value of 2**3.

 */
#include <math.h>
#include <stdio.h>

int main(void)
{
   double x, y, z;

   x = 2.0;
   y = 3.0;
   z = pow(x,y);

   printf("%lf to the power of %lf is %lf\n", x, y, z);
}
Output: 
2.000000 to the power of 3.000000 is 8.000000

Related information