ATAN(3M) Mathematical Library Functions ATAN(3M)

NAME

atan, atanf, atanl - arc tangent function

SYNOPSIS

c99 [ flag... ] file... -lm [ library... ]
#include <math.h>

double atan(double x);


float atanf(float x);


long double atanl(long double x);

DESCRIPTION

These functions compute the principal value of the arc tangent of x.

RETURN VALUES

Upon successful completion, these functions return the arc tangent of
x in the range [-pi/2,pi/2] radians.


If x is NaN, NaN is returned.


If x is +-0, x is returned.


If x is +-Inf, +-pi/2 is returned.

ERRORS

No errors are defined.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


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

SEE ALSO

math.h(3HEAD), atan2(3M), isnan(3M), tan(3M), attributes(7),
standards(7)

SunOS 5.11 July 12, 2006 ATAN(3M)