Jump to content United States-English
HP.com Home Products and Services Support and Drivers Solutions How to Buy
» Contact HP
More options
HP.com home
HP-UX Reference > A

atan(3M)

HP-UX 11i Version 3: February 2007
» 

Technical documentation

» Feedback
Content starts here

 » Table of Contents

 » Index

NAME

atan(), atanf(), atanl(), atanw(), atanq() — arctangent functions

SYNOPSIS

#include <math.h>

double atan(double x);

float atanf(float x);

HP Integrity Server Only

long double atanl(long double x);

extended atanw(extended x);

quad atanq(quad x);

DESCRIPTION

atan() returns the arctangent of x, in the range -π/2 to π/2.

atanf() is a float version of atan(); it takes a float argument and returns a float result.

Integrity Server Only

atanl() is a long double version of atan(); it takes a long double argument and returns a long double result.

atanw() is an extended version of atan(); it takes an extended argument and returns an extended result.

atanq() is equivalent to atanl() on HP-UX systems.

USAGE

To use these functions compile either with the default -Ae option or with the -Aa and the -D_HPUX_SOURCE options.

To use (for Integrity servers) atanw() or atanq(), compile also with -fpwidetypes.

To use any of these functions, make sure your program includes <math.h>, and link in the math library by specifying -lm on the compiler or linker command line. For more information, see the HP-UX floating-point guide for HP Integrity servers at the following site: http://www.hp.com/go/fp.

PA-RISC Only

Millicode versions of the atan() and atanf() functions 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.

For special cases, the millicode versions return the same values as their standard library counterparts (see the RETURN VALUE section).

RETURN VALUE

atan(±0) returns ±0.

If x is ±INFINITY, atan() returns ±π/2 respectively.

If x is NaN, atan() returns NaN.

Whether atan() raises the inexact exception is unspecified.

ERRORS

No errors are defined.

STANDARDS CONFORMANCE

atan() : SVID3, XPG4.2, ANSI C, ISO/IEC C99 (including Annex F, ``IEC 60559 floating-point arithmetic'')

atanf(), atanl() : ISO/IEC C99 (including Annex F, ``IEC 60559 floating-point arithmetic'')

Printable version
Privacy statement Using this site means you accept its terms Feedback to webmaster
© 1983-2007 Hewlett-Packard Development Company, L.P.