Comment on “Parameter identification and synchronization of fractional-order chaotic systems” [Commun Nonlinear Sci Numer Simulat 2012;17:305–16]

This paper comments on the recently published work related to parameter identification of fractional-order chaotic systems [1]. In this note, it is shown that according to the sensitivity issues of chaotic systems to their initial conditions, the criteria for the cost function to be acceptable are not satisfied.

► Parameter identification is an essential part in chaos control and synchronization. ► To evaluate the accuracy of the estimation a fitness function is needed. ► Some works try to maximize their defined fitness function by optimization techniques. ► They use similarity between time series in time domain as objective function. ► Because of the butterfly effect, these kinds of objective functions are not proper.