“…where the set of constants {k 1 , k 2 }, and p the estimate of p, will be determined later. In general, the nonlinear coupled systems (1) and (4) are known as the master and the slave systems, respectively. We want y → x, as t → ∞, when p = p. In other words, we need to find another set of differential equations for vector p of (4), such that (y, p) → (x, p), as long as t → ∞.…”