Given the length of the general definition, a more compact notation is to use boldface for tuples (or vectors) of the variables, thus q = (q 1, q 2,..., q n), ζ = (ζ 1, ζ 2,..., ζ s), p = (p 1, p 2,..., p n), and d ζ / dt = (dζ 1 / dt, dζ 2 / dt,..., dζ s / dt), so that