Matlab: Vertical black line in bode diagram

What does the vertical black line in the bode diagram with multiple functions stand for? for example: >>figure, bode(c1,d1,d2,d3,d4,d5)

Both in the phase and magnitude diagrams.

Answer 1

[Paulo Silva]

That seems to appear only for discrete systems (c2d with Ts for sampling), I can't find documentation about it but it appears related to the nyquist rate and the frequency value of the black line seems to be pi*1/Ts

[Siddharth Jawahar]

Hi Amlaith,

Paulo is right, this represents the nyquist frequency of the system. Documentation is here in the last line of this section:

https://www.mathworks.com/help/control/ref/bode.html?s_tid=srchtitle#bvkcuu1

Sid