# atan(3m) [sunos man page]

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

NAME
atan, atanf, atanl - arc tangent function

SYNOPSIS
cc [ 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 [-/2,/2] radians.

If x is NaN, NaN is returned.

If x is +-0, x is returned.

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

ERRORS
No errors are defined.

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

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

atan2(3M), isnan(3M), math.h(3HEAD), tan(3M), attributes(5), standards(5)

SunOS 5.10							    1 Sep 2002								  atan(3M)```

## Check Out this Related Man Page

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

NAME
atan, atanf, atanl - arc tangent function

SYNOPSIS
cc [ 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 [-/2,/2] radians.

If x is NaN, NaN is returned.

If x is +-0, x is returned.

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

ERRORS
No errors are defined.

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

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