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pow(3) [opendarwin man page]

POW(3)							   BSD Library Functions Manual 						    POW(3)

NAME
pow -- power function SYNOPSIS
#include <math.h> double pow(double x, double y); DESCRIPTION
The pow() functions compute x raised to the power y. SPECIAL VALUES
pow(+-0, y) returns +-infinity and raises the "divide-by-zero" floating-point exception for y an odd integer < 0. pow(+-0, y) returns +infinity and raises the "divide-by-zero" floating-point exception for y < 0 and not an odd integer. pow(+-0, y) returns +-0 for y an odd integer > 0. pow(+-0, y) returns +0 for y > 0 and not an odd integer. pow(-1, +-infinity) returns 1. pow(1, y) returns 1 for any y, even a NaN. pow(x, +-0) returns 1 for any x, even a NaN. pow(x, y) returns a NaN and raises the "invalid" floating-point exception for finite x < 0 and finite non-integer y. pow(x, -infinity) returns +infinity for |x| < 1. pow(x, -infinity) returns +0 for |x| > 1. pow(x, +infinity) returns +0 for |x| < 1. pow(x, +infinity) returns +infinity for |x| > 1. pow(-infinity, y) returns -0 for y an odd integer < 0. pow(-infinity, y) returns +0 for y < 0 and not an odd integer. pow(-infinity, y) returns -infinity for y an odd integer > 0. pow(-infinity, y) returns +infinity for y > 0 and not an odd integer. pow(+infinity, y) returns +0 for y < 0. pow(+infinity, y) returns +infinity for y > 0. A domain error occurs if x is finite and negative and y is finite and not an integer. A domain error can occur if x is 0 and y less than or equal to 0. Range errors may occur. SEE ALSO
math(3), infnan(3) STANDARDS
The pow() function conforms to ISO/IEC 9899:1999(E). 4th Berkeley Distribution July 12, 2003 4th Berkeley Distribution

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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); 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; 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 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 mathemat- ically 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. CONFORMING TO
C99, POSIX.1-2001. The variant returning double also conforms to SVr4, 4.3BSD, C89. BUGS
For a pole error, errno is set to EDOM; POSIX.1 says it should be set to ERANGE. 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. SEE ALSO
cbrt(3), cpow(3), sqrt(3) COLOPHON
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. 2008-08-10 POW(3)
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