HP-UX Reference (11i v1 00/12) - 3 Library Functions N-Z (vol 7)
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STANDARD Printed by: Nora Chuang [nchuang] STANDARD
/build/1111/BRICK/man3/nan.3m
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p
pow(3M) pow(3M)
NAME
pow(), powf() - power functions
SYNOPSIS
#include <math.h>
double pow(double x, double y);
float powf(float x, float y);
DESCRIPTION
The pow() function returns x
y
.Ifx is negative, y must be an integer value.
The powf() function is a float version of pow(); it takes float arguments and returns a float
result. To use this function, compile either with the default -Ae option or with the -Aa and
-D_HPUX_SOURCE options.
powf() is not specified by any standard, but it is named in accordance with the conventions specified in
the "Future Library Directions" section of the ANSI C standard.
To use these functions, make sure your program includes <
math.h>, and link in the math library by speci-
fying
-lm on the compiler or linker command line.
Millicode versions of the pow() function are available. Millicode versions of math library functions are
usually faster than their counterparts in the standard library. To use these versions, compile your program
with the +Olibcalls or the +Oaggressive optimization option.
If an error occurs, the millicode versions return the value described in the RETURN VALUE section, but do
not set
errno.
For more information, see the HP-UX Floating-Point Guide.
RETURN VALUE
If x and y are both zero,
pow() returns 1.0.
If x or y is NaN, pow() returns NaN.
If the correct value after rounding would be smaller in magnitude than MINDOUBLE, pow() returns zero.
If x is zero and y is less than zero,
pow() returns −HUGE_VAL and sets errno
to [EDOM].
If x is less than zero and y is not an integer,
pow() returns NaN and sets errno
to [EDOM].
If the correct value would overflow,
pow() returns ±HUGE_VAL and sets errno to [ERANGE].
ERRORS
If
pow() fails, errno is set to one of the following values.
[EDOM] x is zero and y is less than zero.
[EDOM] x is less than zero and y is not an integer.
[ERANGE] The correct value would overflow.
SEE ALSO
cbrt(3M), exp(3M), log(3M), sqrt(3M), math(5), values(5).
STANDARDS CONFORMANCE
pow(): SVID3, XPG4.2, ANSI C
HP-UX Release 11i: December 2000 − 1 − Section 3−−617
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