Simulink versus calling an ODE solver in the script: which is better? In control engineering problems, especially optimal control problems, we deal with solving a set of ordinary differential equations. There are two ways to do: (i). using Simulink, (ii). calling an ODE solver in the script. What is the difference in results, and which one is better is the matter of concern for many scholars. Actually, there is no difference in simulation results as long as you are using the same solver in both cases with same step size. The results for certain benchmark equations are shown here. Then, which one is better when they give same results. I feel Simulink is better for three reasons. (i) Easiness and simplicity : Simulink provides an intuitive interface that you can model a plant and design various controllers for different scenarios without even thinking about rewriting the system equations y'=f(x,y), this is because you can model a system in Simulink without thinking in terms of first order differential equations, just it is: signal lines represent data and blocks represent the functions acting on this data. (ii). Hardware implementation: By switching over to fixed-step solver, you can generate C code using Simulink Coder/Embedded Coder of the model and implementation on microcontroller, DSP etc. become easy and straight forward. (iii). Extension Products: Simscape, SimHydraulics etc. can be utilized to model physical systems like circuits, hydraulic systems, power systems etc., and integrated with Simulink model easily.