public static function pi(): Decimal
    {
        if (null === self::$PI) {
            self::$PI = Decimal::fromString(
                "3.14159265358979323846264338327950"
            );
        }
        return self::$PI;
    }
public static function pi(): Decimal
    {
        if (null === self::$PI) {
            self::$PI = Decimal::fromString(
                "3.14159265358979323846264338327950"
            );
        }
        return self::$PI;
    }
public static function pi ( ) : Decimal { if ( null === self :: $ PI ) { self :: $ PI = Decimal :: fromString ( "3.14159265358979323846264338327950" ) ; } return self :: $ PI ; }
Returns the Pi number.
@return Decimal
Returns the Pi number .