#!/usr/bin/env python

#

# margin_test.py - test suit for stability margin commands

# RMM, 15 Jul 2011

import unittest

import numpy as np

from control.xferfcn import TransferFunction

from control.statesp import StateSpace

from control.margins import *

class TestMargin(unittest.TestCase):

"""These are tests for the margin commands in margin.py."""

def setUp(self):

self.sys1 = TransferFunction([1, 2], [1, 2, 3])

self.sys2 = TransferFunction([1], [1, 2, 3, 4])

self.sys3 = StateSpace([[1., 4.], [3., 2.]], [[1.], [-4.]],

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

def test_stability_margins(self):

gm, pm, sm, wg, wp, ws = stability_margins(self.sys1);

gm, pm, sm, wg, wp, ws = stability_margins(self.sys2);

gm, pm, sm, wg, wp, ws = stability_margins(self.sys3);

def test_phase_crossover_frequencies(self):

omega, gain = phase_crossover_frequencies(self.sys2)

np.testing.assert_array_almost_equal(omega, [1.73205, 0.])

np.testing.assert_array_almost_equal(gain, [-0.5, 0.25])

tf = TransferFunction([1],[1,1])

omega, gain = phase_crossover_frequencies(tf)

np.testing.assert_array_almost_equal(omega, [0.])

np.testing.assert_array_almost_equal(gain, [1.])

# testing MIMO, only (0,0) element is considered

tf = TransferFunction([[[1],[2]],[[3],[4]]],

[[[1, 2, 3, 4],[1,1]],[[1,1],[1,1]]])

omega, gain = phase_crossover_frequencies(tf)

np.testing.assert_array_almost_equal(omega, [1.73205081, 0.])

np.testing.assert_array_almost_equal(gain, [-0.5, 0.25])

def suite():

return unittest.TestLoader().loadTestsFromTestCase(TestMargin)

if __name__ == "__main__":

unittest.main()