Math Functions
PHP Manual

pi

Get value of pi

Description

float pi ( void )

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.

Return Values

The value of pi as float.

Examples

Example #1 pi example

<?php
echo pi(); // 3.1415926535898
echo M_PI; // 3.1415926535898
?>