Definition: The Atan () Function finds the arctangent of a number. In Atan (X), the value of X can be any positive or negative number, and the result will be between PI/2 and -PI/2. The function will returns the angle, expressed in radians, whose tangent is X.
Also Known As: Arctangent, Arc tangent
Examples:
<?php
echo(atan(-0.5) . "<br />");
echo(atan(-1) . "<br />");
echo(atan(0) . "<br />");
echo(atan(1) . "<br />");
echo(atan(2))
?>
This will give you the results:
-0.46364760900081
-0.78539816339745
0
0.78539816339745
1.1071487177941
