I was hesitant to answer your question because it shows that you need to review the basics. However, hopefully this will encourage you to do just that!

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The $s$ in $H(s)$ is a **complex number** $$s = \sigma + j\omega$$ where $\sigma$, the real part, represents a *damping* factor and $j\omega$, the imaginary part, represents an oscillatory component (for which $\omega$ is the angular frequency).

For sinusoidal steady-state analysis, we are interested in the behavior of the system at different frequencies but without the damping effect ($\sigma = 0$).

With that said, you only need minimal changes to your script:

```matlab
omega = 0:0.01:50;
s = 1i * omega;
```

[![enter image description here][1]][1]

 


  [1]: https://i.sstatic.net/sQwtp.png