“…In the control of stochastic dynamical systems, to reshape the PDFs of the output is necessary for tracking the target PDFs [Sun, 2006;Guo et al, 2008;Hong et al, 2005;Elbeyli et al, 2005], therefore online estimation of the output PDF is important and in [Guo & Wang, 2005], B-spline approximation of the output PDFs is used to design PID controller for controlling the stochastic dynamics. The PDF estimation can also be used to test the efficiency of the designed chaotic circuits with prescribed random properties given in [Chua et al, 1990].…”