pi
    (PHP 3, 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().
    
     
Example 1. pi() example 
<?php echo pi(); // 3.1415926535898 echo M_PI; // 3.1415926535898 ?>
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