Question

The method which provides considerable flexibility in finding the Liapunov’s function is:

(a) Krasovskii’s method

(b) Variable gradient method

(c) Constant method

(d) Non-variable gradient method

I got this question during an interview.

The above asked question is from The Direct Method and  Constructing of Liapunov for the Linear and Non-Linear System in section Liapunov’s Stability Analysis of Control Systems

Answer 1

The correct answer is (b) Variable gradient method

For explanation I would say: Variable gradient method provides considerable flexibility in finding the Liapunov’s function as the quadratic form approach is too restrictive.