I'm having problems with the ax parameters of the rlocus function #623
Description
I was trying today to plot the root locus of a transfer function, but wanted to pass a specific axes object to it, so I tried to use the ax parameter of the rlocus function:
from control import *
import matplotlib.pyplot as plt
s = tf([1, 0], 1)
G = 1/(s*(s+1))
fig, ax = plt.subplots(dpi=200)
rlocus(G, ax=ax)
But when doing this, the following error was raised:
---------------------------------------------------------------------------
UnboundLocalError Traceback (most recent call last)
<ipython-input-1-80498c4b1a54> in <module>
6
7 fig, ax = plt.subplots(dpi=200)
----> 8 rlocus(G, ax=ax)
~\anaconda3\lib\site-packages\control\rlocus.py in root_locus(sys, kvect, xlim, ylim, plotstr, plot, print_gain, grid, ax, **kwargs)
173
174 if print_gain and not sisotool:
--> 175 fig.canvas.mpl_connect(
176 'button_release_event',
177 partial(_RLClickDispatcher, sys=sys, fig=fig,
UnboundLocalError: local variable 'fig' referenced before assignment
Control version: 0.9.0