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```POW(3)			   Linux Programmer's Manual			POW(3)

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);

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.

RETURN VALUE
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 do-
main 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  mathemati-
cally 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	infin-
ity, 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	infin-
ity, the	result is positive infinity.

If x is negative	infinity, and y	is an odd integer less than 0, the re-
sult 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 oc-
curs  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	float-
ing-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.

CONFORMING TO
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_IN-
VALID)  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 oc-
curs, glibc's pow() generates a bogus invalid floating-point  exception
(FE_INVALID) in addition	to the overflow	or underflow exception.

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

COLOPHON
This  page  is  part of release 3.74 of the Linux man-pages project.  A
description of the project, information about reporting bugs,  and  the
latest	  version     of     this    page,    can    be	   found    at
http://www.kernel.org/doc/man-pages/.

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

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | BUGS | SEE ALSO | COLOPHON

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