A general method to derive Lyapunov functions for non-linear systems

Abstract A method is proposed that derives suitable Lyapunov functions for a general class of non-linear system expressed in state variables as nfirst-order non-linear differential equations. Lyapunov functions for several third- and fourth-order nonlinear systems, derived using the proposed method are identical to those obtained by Ogurtsov (1958, 1959)and Barbasin (1960), by an analogy with linear systems; by Barbasin (1960), using the method of separation of variables; and by Siddiqee (1968), applying a qualitative approach.