Is it possible to generate proper Root Locus Plots with Python 3?

Question

I am trying to generate root locus plots via Python 3, but the graphs that Python produces don't seem to be complete.

Here is the system to be implemented for the Root Locus;

Here is my code for the Root Locus plot;

import numpy as np
from matplotlib import pyplot as plt 
import control

%matplotlib

G = control.TransferFunction((1, 1.5), (1, 11, 10, 0))

rlist, klist = control.rlocus(G)

plt.show()

And here is the graph I get;

But from the textbook I'm using, this is the plot that they have;

Is there a way to get Python to provide a plot which is closer the actual solution, or is this the best approximation possible with Python right now?

Answer 1

Try this,

import numpy as np
from matplotlib import pyplot as plt 
import control

G = control.TransferFunction((1, 1.5), (1, 11, 10, 0))

rlist, klist = control.rlocus(G, kvect=np.linspace(100.0, -100.0, num=1000))

plt.show()

Output:

You can choose a more optimal kvect range depending on your transfer function.

kvect (list or ndarray, optional) – List of gains to use in computing diagram

Source: control.root_locus Documentation