Identification of Unknown Parameters and Orders via Cuckoo Search Oriented Statistically by Differential Evolution for Noncommensurate Fractional-Order Chaotic Systems

Figure 2

Some examples of the tree structures in GP evolutions.

(a) sin𝑥+𝑦𝑧

(b) sin(𝑥−𝑦)⋅ln𝑧−(𝑦+𝑥𝑧)

(c) 𝒟^𝑝_𝑡𝑥=𝑦𝑧

(d) 𝒟^𝑝_𝑡(𝑥−𝑦)=𝑦+𝑥𝑧

(e) 𝒟^𝑝1_𝑡(𝑥−𝑦)=𝑦+𝑧𝒟^𝑝2_𝑡𝑥

(f) Illegal candidates