A method of evaluating zero conditional Lyapunov exponent from time series

A new method of evaluating zero conditional Lyapunov exponent is proposed that is valid for dynamic systems exhibiting periodic dynamics, in the presence of noise, and for coupled chaotic systems. The proposed method is based on analysis of the time series (phase difference versus time) of a system under consideration and allows a zero conditional Lyapunov exponent in a supercritical region of the control parameter to be estimated with sufficiently high accuracy. The main results are illustrated by the example of systems exhibiting periodic dynamics in the presence of noise.