NAME¶

pow, powf, powl - power functions

LIBRARY¶

Math library (libm, -lm)

SYNOPSIS¶

#include <math.h>

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

powf(), powl():

    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L


        || /* Since glibc 2.19: */ _DEFAULT_SOURCE


        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION¶

These functions return the value of x raised to the power of y.

RETURN VALUE¶

On success, these functions return the value of x to the power of y.

If the result overflows, a range error occurs, and the functions return HUGE_VAL, HUGE_VALF, or HUGE_VALL, respectively, with the mathematically correct sign.

If result underflows, and is not representable, a range error occurs, and 0.0 with the appropriate sign is returned.

If x is +0 or -0, and y is an odd integer less than 0, a pole error occurs and HUGE_VAL, HUGE_VALF, or HUGE_VALL, is returned, with the same sign as x.

If x is +0 or -0, and y is less than 0 and not an odd integer, a pole error occurs and +HUGE_VAL, +HUGE_VALF, or +HUGE_VALL, is returned.

If x is +0 (-0), and y is an odd integer greater than 0, the result is +0 (-0).

If x is 0, and y greater than 0 and not an odd integer, the result is +0.

If x is -1, and y is positive infinity or negative infinity, the result is 1.0.

If x is +1, the result is 1.0 (even if y is a NaN).

If y is 0, the result is 1.0 (even if x is a NaN).

If x is a finite value less than 0, and y is a finite noninteger, a domain error occurs, and a NaN is returned.

If the absolute value of x is less than 1, and y is negative infinity, the result is positive infinity.

If the absolute value of x is greater than 1, and y is negative infinity, the result is +0.

If the absolute value of x is less than 1, and y is positive infinity, the result is +0.

If the absolute value of x is greater than 1, and y is positive infinity, the result is positive infinity.

If x is negative infinity, and y is an odd integer less than 0, the result is -0.

If x is negative infinity, and y less than 0 and not an odd integer, the result is +0.

If x is negative infinity, and y is an odd integer greater than 0, the result is negative infinity.

If x is negative infinity, and y greater than 0 and not an odd integer, the result is positive infinity.

If x is positive infinity, and y less than 0, the result is +0.

If x is positive infinity, and y greater than 0, the result is positive infinity.

Except as specified above, if x or y is a NaN, the result is a NaN.

ERRORS¶

See math_error(7) for information on how to determine whether an error has occurred when calling these functions.

The following errors can occur:

Domain error: x is negative, and y is a finite noninteger

errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised.

Pole error: x is zero, and y is negative

errno is set to ERANGE (but see BUGS). A divide-by-zero floating-point exception (FE_DIVBYZERO) is raised.

Range error: the result overflows

errno is set to ERANGE. An overflow floating-point exception (FE_OVERFLOW) is raised.

Range error: the result underflows

errno is set to ERANGE. An underflow floating-point exception (FE_UNDERFLOW) is raised.

ATTRIBUTES¶

For an explanation of the terms used in this section, see attributes(7).

STANDARDS¶

C11, POSIX.1-2008.

HISTORY¶

C99, POSIX.1-2001.

The variant returning double also conforms to SVr4, 4.3BSD, C89.

BUGS¶

SEE ALSO¶

cbrt(3), cpow(3), sqrt(3)