import controlimport matplotlib.pyplot as pltGp = control.tf([2],[1,3,2,0])Gz = control.c2d(Gp,0.05)mag, phase, omega = control.bode(Gz)print(control.margin(Gz))print(control.margin([mag, phase, omega]))plt.grid()plt.show()

(31.505480557979414, inf, 3.7736323313549196, nan)(inf, 177.40890111291884, nan, 0.749329697586152)

import control as ct import numpy as npimport matplotlib.pyplot as pltimport mathfrom scipy import interpolateGp = ct.tf([2],[1,3,2,0])Gz = ct.c2d(Gp, 0.05)mag, phase, omega = ct.bode(Gz)p_w = interpolate.interp1d(phase, omega)p_m = interpolate.interp1d(phase, mag)print("Gain margin %.3f at %.3f rad/s"%(1/p_m(-np.pi), p_w(-np.pi)))m_w = interpolate.interp1d(mag, omega)m_p = interpolate.interp1d(mag, phase)print("Phase margin %.3f\N{DEGREE SIGN} at %.3f rad/s"%(math.degrees(m_p(1)+np.pi), m_w(1)))

Gain margin 2.771 at 1.367 rad/sPhase margin 31.394° at 0.753 rad/s