Fix nyquist plotting from FrequencyResponseData by wueestry · Pull Request #996 · python-control/python-control
This is a good fix, but I think we could add a bit better support if there are multiple FRD systems with different frequencies and not explicit frequency list given. For example, try this:
import control as ct
sys = ct.rss(4, 1, 1)
sys1 = ct.frequency_response(sys, np.logspace(-1, 1, 10))
sys2 = ct.frequency_response(sys, np.logspace(-2, 2, 10))
ct.bode_plot([sys1, sys2]) # works OK
ct.nyquist_plot(sys1, np.logspace(-1, 1, 10)) # works OK
ct.nyquist_plot(sys2, np.logspace(-1, 1, 10)) # generates error (as it should)
ct.nyquist_plot([sys1, sys2]) # generates error (does it need to?)
It seems to me that the last case should work OK and just plot each system independently, without needing a common frequency range (as it does for Bode plots).