# pi

(PHP 4, PHP 5)

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
?>`