Is MATLAB giving a wrong root locus? Maybe a bug?
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Daniel Koslopp
on 26 Feb 2015
Commented: Arjun Sheshadri
on 18 Apr 2019
Hello, I am trying to obtain a root locus with the following code which has 3 poles and 1 zero:
if true
clear all
close all
clc
num = [-0.1654 -0.0367]
den = [1 3.27 -20.23 -24.95]
rlocus(num,den)
axis([-10 10 -2.5 2.5])
end
The problem is that ML is giving me a strange result because it has a path on the right side of the biggest pole. The figure shows:
I tested in other software and it gave different results that seems more reasonable, like this one:
So, I am doing something wrong or it is a bug? My version is R2014a.
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Accepted Answer
Arkadiy Turevskiy
on 18 Mar 2015
There is no error with your code or bug in MATLAB. It just seems you got the sign wrong. If you do rlocus(-num,den), you will get the root locus you expected to see.
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