Get the inverse hyperbolic tangent of different numbers in PHP

Description

The following code shows how to get the inverse hyperbolic tangent of different numbers.

Example

// w  ww  . ja  v a  2 s .c  om
<?php
    echo(atanh(M_PI_4) . "<br>");
    echo(atanh(0.50) . "<br>");
    echo(atanh(-0.50) . "<br>");
    echo(atanh(1) . "<br>");
    echo(atanh(-1));
?>

The code above generates the following result.