Example: Let us consider the general two-stage Runge-Kutta method obtained by getting in (3.12). Then, by (3.17), (3.23) and (3.32), the local truncation error is
(3.34)
If the order is two, then (3.24) must hold, and we obtain
(3.35)
Thus the principal error function for the general second order Runge-Kutta method is given by
in (3.12). Then, by (3.17), (3.23) and (3.32), the local truncation error is 
