(PHP 4, PHP 5, PHP 7)
pi — Get value of pi
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().
The value of pi as float.
Example #1 pi() example
<?php
echo pi(); // 3.1415926535898
echo M_PI; // 3.1415926535898
?>
Pi is often usefull in con/sin/tan functions..
There are also other Pi related constants.
These are most of them:
M_PI = 3.14159265358979323846 // pi
// The following were added in PHP 4.0.0
M_PI_2 = 1.57079632679489661923 // pi/2
M_PI_4 = 0.78539816339744830962 // pi/4
M_1_PI = 0.31830988618379067154 // 1/pi
M_2_PI = 0.63661977236758134308 // 2/pi
M_SQRTPI = 1.77245385090551602729 // sqrt(pi) (Only in PHP 4.0.2+)
M_2_SQRTPI = 1.12837916709551257390 // 2/sqrt(pi)
You can print pi in a more complicating way. In the code bellow we save pi as a variable and print its first 4 digits.
$n = pi();
echo round ($n,4);
