# pow(3m) [sunos man page]

```pow(3M) 						  Mathematical Library Functions						   pow(3M)

NAME
pow, powf, powl - power function

SYNOPSIS
cc [ flag... ] file... -lm [ library... ]
#include <math.h>

double pow(double x, double y);

float powf(float x, float y);

long double powl(long double x, long double y);

DESCRIPTION
These functions compute the value of x raised to the power y, x**y. If x is negative, y must be an integer value.

RETURN VALUES
Upon successful completion, these functions return the value of x raised to the power y.

For  finite values of x < 0, and finite non-integer values of y, a domain error occurs and either a NaN (if representable), or an implemen-
tation-defined value shall be returned.

If the correct value would cause overflow, a range error occurs and pow(), powf(), and powl() return HUGE_VAL,  HUGE_VALF,  and	HUGE_VALL,
respectively.

If x or y is a NaN, a NaN is returned unless:

o  For  any finite value of y, if x is +1 and y is either +-Inf or NaN and the application is SUSv3-conforming (see standards(5)), 1.0 is
returned.

o  For any value of x (including NaN), if y is +-0, 1.0 is returned.

For any odd integer value of y > 0, if x is +-0, +-0 is returned.

For y > 0 and not an odd integer, if x is +-0, +0 is returned.

If x is -1, and y is +-Inf, 1.0 is returned.

For |x| < 1, if y is -Inf, +Inf is returned.

For |x| > 1, if y is -Inf, +0 is returned.

For |x| < 1, if y is +Inf, +0 is returned.

For |x| > 1, if y is +Inf, +Inf is returned.

For y an odd integer < 0, if x is -Inf, -0 is returned.

For y < 0 and not an odd integer, if x is -Inf, +0 is returned.

For y an odd integer > 0, if x is -Inf, -Inf is returned.

For y > 0 and not an odd integer, if x is -Inf, +Inf is returned.

For y < 0, if x is +Inf, +0 is returned.

For y > 0, if x is +Inf, +Inf is returned.

For y an odd integer < 0, if x is +-0, a pole error occurs and +-HUGE_VAL, +-HUGE_VALF, and +-HUGE_VALL are returned for pow(), powf(), and
powl(), respectively.

For  y  < 0 and not an odd integer, if x is +-0, a pole error occurs and HUGE_VAL, HUGE_VALF, and HUGE_VALL are returned for pow(), powf(),
and powl(), respectively.

For exceptional cases, matherr(3M) tabulates the values to be returned by pow() as specified by SVID3 and XPG3.

ERRORS
These functions will fail if:

Domain Error    The value of x is negative and y is a finite non-integer.

If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the invalid floating-point exception is raised.

The pow() function sets errno to EDOM if the value of x is negative and y is non-integral.

Pole Error      The value of x is 0 and y is negative.

If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the divide-by-zero floating-point  exception	is
raised.

Range Error     The result overflows.

If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the overflow floating-point exception is raised.

The pow() function sets errno to EDOM if the value to be returned would cause overflow.

USAGE
An  application	wanting  to  check  for  exceptions should call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if
fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an exception  has  been  raised.  An  application  should
either examine the return value or check the floating point exception flags to detect exceptions.

An  application can also set errno to 0 before calling pow(). On return, if errno is non-zero, an error has occurred. The powf() and powl()
functions do not set errno.

ATTRIBUTES
See attributes(5) for descriptions of the following attributes:

+-----------------------------+-----------------------------+
|      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
+-----------------------------+-----------------------------+
|Interface Stability	     |Standard			   |
+-----------------------------+-----------------------------+
|MT-Level		     |MT-Safe			   |
+-----------------------------+-----------------------------+