I've just begun studying nonlinear systems in my spare time. I'm using 'Nonlinear System Theory' by Rugh. My question is if there is a universal way to find the Lyapunov function of an arbitrary system. It doesn't have to be the easiest way, just a universal method that always works.
This is merely a question of curiosity.
Also, if anyone has any suggestion for good self-study books for nonlinear systems, feel free to mention them.
Perhaps I should rephrase: if a Lyapunov function exists, is there a universal way to find it that usually works. Existence is important.