PI(3) 1 PI(3) pi - Get value of piSYNOPSISfloat pi (void )DESCRIPTIONReturns 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(3).RETURN VALUESThe value of pi as float.EXAMPLESExample #1 pi(3) example <?php echo pi(); // 3.1415926535898 echo M_PI; // 3.1415926535898 ?> PHP Documentation Group PI(3)