## NAME

atan2 - arc tangent function of two variables

## SYNOPSIS

**#include** **<math.h>**
**double** **atan2(double** **y,** **double** **x);**

## DESCRIPTION

The **atan2()** function calculates the arc tangent of the two
variables **x** and **y**. It is similar to calculating the arc
tangent of **y** / **x**, except that the signs of both arguments
are used to determine the quadrant of the result.

## RETURN VALUE

The **atan2()** function returns the result in radians, which is
between -PI and PI (inclusive).

## CONFORMING TO

SVID 3, POSIX, BSD 4.3, ISO 9899

## SEE ALSO

**acos**(3), **asin**(3), **atan**(3),