from numpy import inf, nan

from numpy.testing import assert_allclose

from control.frdata import FrequencyResponseData

from control.margins import (margin, phase_crossover_frequencies,

stability_margins)

from control.statesp import StateSpace

from control.xferfcn import TransferFunction

from control.exception import ControlMIMONotImplemented

from control import ControlMIMONotImplemented, FrequencyResponseData, \

StateSpace, TransferFunction, margin, phase_crossover_frequencies, \

stability_margins

s = TransferFunction.s

out = margin((mag, phase*180/np.pi, omega_))

assert_allclose(out, np.array(refout)[[0, 1, 3, 4]], atol=1.5e-3)

@pytest.mark.parametrize(

'tfargs, omega_ref, gain_ref',

[(([1], [1, 2, 3, 4]), [1.7325, 0.], [-0.5, 0.25]),

(([1], [1, 1]), [0.], [1.]),

(([2], [1, 3, 3, 1]), [1.732, 0.], [-0.25, 2.]),

((np.array([3, 11, 3]) * 1e-4, [1., -2.7145, 2.4562, -0.7408], .1),

[1.6235, 0.], [-0.28598, 1.88889]),

(([200.0], [1.0, 21.0, 20.0, 0.0]),

[4.47213595, 0], [-0.47619048, inf]),

])

@pytest.mark.filterwarnings("error")

def test_phase_crossover_frequencies(tfargs, omega_ref, gain_ref):

"""Test phase_crossover_frequencies() function"""

sys = TransferFunction(*tfargs)