from sympy.abc import a, b, c, d, s
from sympy.physics.control.lti import TransferFunction
from spb import *
tf1 = TransferFunction(s**2 + 1, s**4 + 4*s**3 + 6*s**2 + 5*s + 2, s)
tf2 = TransferFunction(s**2 + b, s**4 + a*s**3 + b*s**2 + c*s + d, s)
params = {
    a: (3, 0, 5),
    b: (5, 0, 10),
    c: (4, 0, 8),
    d: (3, 0, 5),
}
graphics(
    control_axis(),
    pole_zero(tf1, label="A"),
    pole_zero(tf2, label="B", params=params),
    grid=False, xlim=(-4, 1), ylim=(-4, 4),
    xlabel="Real", ylabel="Imaginary")