In this chapter, the ZG controllers for explicit and implicit tracking control of a double-integrator (DI) system are designed and presented. In addition, we conduct the corresponding computer simulations with different values of the design parameter λ used to illustrate the efficacy of ZG controllers. However, although the ZG controllers are powerful, there is still a challenge in the simulation practice. Specifically, different settings of simulation options in MATLAB ordinary differential equation (ODE) solvers may lead to different simulation results (e.g., failure and success). For better comparison, the successful and failed simulation results are both presented. The differences in simulation results remind us to pay more attention to MATLAB defaults and options during conducting such simulations.