Why can't I get the same plot as the official tutorial video? (non-minimal phase system)

The link is: https://youtu.be/jGEkmDRsq_M

2:41 I use the same code as Brian, But the bode plot are different. So maybe I am wrong? or the video uses wrong figure? I can't figure it out.

Can anyone help me check it?

>>G=tf([1 2],[1 3 1]);G_delay=tf([1 2],[1 3 1],'InputDelay', 1);G_RHP_zero=tf([-1 2],[1 3 1]);bode(G);hold all; bode(G_delay);bode(G_RHP_zero)

4:18 The code in the video reports an error.

>>step(G,G_delay,G_RHP_zero)

Error using DynamicSystem/step (line 95)Plots must be of the same type and size to be superimposed.

Answer 1

[Paul]

I get the same Bode plots. What's different about yours? Also, you can do this with one Bode command

bode(G,G_RHP_zero,G_delay)

To deal with the error on the step command, you need to either "hold off" the axes with the Bode plots, or do clf, or open a new figure for the step response plots.

[He Li]

My bode plot look like this. This really confuse me... There is no fluctuation.

[Paul]

The plots in the video have the phase wrapped to be between +-180 deg. To get the same in your plot

1. Right click in the gain or the phase plot
2. Select "Properties"
3. Options tab
4. Check "Wrap phase"

[He Li]

Thank you so much.