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Negative Values in Step Response

Asked by Kenneth

Kenneth (view profile)

on 26 May 2013

Hi guys,

I just noticed something interesting on MATLAB.

I was working with a transfer function, and I inserted a delay using a Pade approximation, and plotted the step response. At first glance, it seems just like any other step response, however when i zoomed in on the origin, I noticed that it slightly dips into negative values before coming up.

I've never noticed this before. Anyone have any idea why it does this?

0 Comments

Kenneth

Kenneth (view profile)

1 Answer

Answer by Azzi Abdelmalek

Azzi Abdelmalek (view profile)

on 26 May 2013
Accepted answer

This is normal, when your transfer function contains positives zeros

example H(p)=(-p+2)/(p^2+2p+1)

step([-1 2],[1 2 1])

3 Comments

Kenneth

Kenneth (view profile)

on 26 May 2013

Hmm indeed it did have a positive zero. Why does it do this though? What does it mean?

Kenneth

Kenneth (view profile)

on 26 May 2013

Interesting stuff, thanks for the info!

Azzi Abdelmalek

Azzi Abdelmalek (view profile)

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