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#### NAME

```       pow, powf, powl - power functions

```

#### 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);

Link with -lm.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

powf(), powl():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
or cc -std=c99

```

#### DESCRIPTION

```       The pow() function returns the value of x raised to the power of y.

```

#### RETURNVALUE

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

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  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 is returned.

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

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 +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 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.

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.

```

#### 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.

```

#### CONFORMINGTO

```       C99, POSIX.1-2001.  The variant returning double also conforms to SVr4, 4.3BSD, C89.

```

#### BUGS

```       In  glibc  2.9  and earlier, when a pole error occurs, errno is set to EDOM instead of the
POSIX-mandated ERANGE.  Since version 2.10, glibc does the right thing.

If x is negative, then large negative or positive y values yield a  NaN  as  the  function
result, with errno set to EDOM, and an invalid (FE_INVALID) floating-point exception.  For
example, with pow(), one sees this behavior when the absolute value of y is  greater  than
about 9.223373e18.

In  version  2.3.2  and earlier, when an overflow or underflow error occurs, glibc's pow()
generates a bogus  invalid  floating-point  exception  (FE_INVALID)  in  addition  to  the
overflow or underflow exception.

```

#### SEEALSO

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

```

#### COLOPHON

```       This  page  is  part of release 3.35 of the Linux man-pages project.  A description of the
project, and information about reporting bugs, can be found at  http://man7.org/linux/man-
pages/.

2010-09-12                                     POW(3)
```