*4.2. Time Waveforms and Trajectories of The System*

The time waveforms of *x*(*t*), *y*(*t*) and *z*(*t*) are reported in Figures 7–9, where the time interval is in *ms*. We see that the oscillations in the figures are non-periodic.

**Figure 7.** The time waveform of *x*(*t*).

**Figure 9.** The time waveform of *z*(*t*).

The trajectories of *x*(*t*), *y*(*t*), *z*(*t*) in 2D and 3D are numerically simulated in Figures 10–13. We see that the trajectory of (*x*(*t*), *y*(*t*)) diverges in a spiral form, but *z*(*t*) converges to the equilibrium point. The trajectories are dense and seem to have no periodic. Thus, chaotic behavior occurs in the modified jerk circuit with Chua's diode. Moreover, the attractor of the system is shown by the blue lines in Figures 10–13. From the 3D plot in Figure 13, we see that the oscillation does not connect with the equilibrium points *E*1, *E*2, *E*3, thus the system has a hidden attractor.

**Figure 10.** The trajectories of (*x*(*t*), *y*(*t*)) in 2D.

**Figure 11.** The trajectories of (*x*(*t*), *z*(*t*)) in 2D.

**Figure 12.** The trajectories of (*y*(*t*), *z*(*t*)) in 2D.
