def test_margin_3input(tsys):
sys, refout, refoutall = tsys
"""Test margin() function with mag, phase, omega input"""
omega = np.logspace(-2, 2, 2000)
mag, phase, omega_ = sys.frequency_response(omega)
out = margin((mag, phase * 180 / np.pi, omega_))
assert_allclose(out, np.array(refout)[[0, 1, 3, 4]], atol=1.5e-3)
def test_zmore_margin(tsys_zmore):
"""Test margins for more tricky systems
Note
----
Matlab gives gain margin 0 for system `type2`, python-control gives inf
Difficult to argue which is right? Special case or different approach?
Edge cases, like `type0` which approaches a gain of 1 for w -> 0, are also
not identically indicated, Matlab gives phase margin -180, at w = 0. For
higher or lower gains, results match.
"""
res = margin(tsys_zmore['sys'] * tsys_zmore['K'])
assert_allclose(res, tsys_zmore['result'], atol=tsys_zmore['atol'])
def test_margin_sys(tsys):
sys, refout, refoutall = tsys
"""Test margin() function with system input"""
out = margin(sys)
assert_allclose(out, np.array(refout)[[0, 1, 3, 4]], atol=1.5e-3)
def test_zmore_margin(tmargin):
"""Test margins for more tricky systems"""
res = margin(tzmore_sys[tmargin['sys']] * tmargin['K'])
assert_allclose(res, tmargin['result'], atol=tmargin['atol'])