public static function gcd($a, $b) {
        return ($b == 0) ? ($a):(self::gcd($b, $a % $b));
    }
public static function gcd($a, $b) {
        return ($b == 0) ? ($a):(self::gcd($b, $a % $b));
    }
public static function gcd ( $ a , $ b ) { return ( $ b == 0 ) ? ( $ a ) : ( self :: gcd ( $ b , $ a % $ b ) ) ; }
Helper function returning the greatest common divisor

@param int $a
@param int $b
@return int
Helper function returning the greatest common divisor