(PHP 3, PHP 4 , PHP 5)
Returns an approximation of pi. The returned float has a precision based on the precision directive in php.ini, which defaults to 14. Also, you can use the M_PI constant which yields identical results to pi().
Example 1. pi() example
<?phpecho pi(); // 3.1415926535898echo M_PI; // 3.1415926535898?>
