atan2()

The atan2() function returns the arc tangent of y/x, in radians.

Syntax

atan2(y,x);

The atan2() function has two parameters. It returns the arc tangent of y/x, in radians. Where x and y are the coordinates of a point (x, y). Both specify a positive or negative number.

Example

The following code uses atan2() to return the arc tangent of (-10,8):

<?php
  echo atan2(-10,8);
?>

This results in the following output:

 -0.89605538457134