# 2-step Runge Kutta method

I just started studying RK method of order 2. I want to know that, " RK method of order 2 and 2 step RK method are same or not?"

• It's not usually called the 'two step RK method', rather, the 'two stage RK method'. Apr 4 '17 at 10:42
• You can easily construct 2-stage RK methods that only have order $1$. I think it starts with order $6$ that there are no p-stage methods of order $p$. Apr 4 '17 at 12:15
• @Mattos y_n+1 = y_n + 1/2(K0+K1) is this a 2 step method or 3 step method? Apr 4 '17 at 16:56
• Two function evaluations = two stages. Apr 6 '17 at 7:45

The usual RK2 requires two evaluations and the error is $O(h^2)$ ($h =$ step size.)