Mar 21, 2020 · Jan 28, 2020 · Mar 18, 2020
diff --git a/control/tests/xferfcn_test.py b/control/tests/xferfcn_test.py
                                             np.zeros((3, 5, 6)))
        np.testing.assert_array_almost_equal(den, denref)

    def test_common_den_nonproper(self):
        """ Test _common_den with order(num)>order(den) """

        tf1 = TransferFunction(
                [[[1., 2., 3.]], [[1., 2.]]],
                [[[1., -2.]], [[1., -3.]]])
        tf2 = TransferFunction(
                [[[1., 2.]], [[1., 2., 3.]]],
                [[[1., -2.]], [[1., -3.]]])

        common_den_ref = np.array([[1., -5., 6.]])

        np.testing.assert_raises(ValueError, tf1._common_den)
        np.testing.assert_raises(ValueError, tf2._common_den)

        _, den1, _ = tf1._common_den(allow_nonproper=True)
        np.testing.assert_array_almost_equal(den1, common_den_ref)
        _, den2, _ = tf2._common_den(allow_nonproper=True)
        np.testing.assert_array_almost_equal(den2, common_den_ref)

    @unittest.skipIf(not slycot_check(), "slycot not installed")
    def test_pole_mimo(self):
        """Test for correct MIMO poles."""

        np.testing.assert_array_almost_equal(p, [-2., -2., -7., -3., -2.])

        # non proper transfer function
        sys2 = TransferFunction(
            [[[1., 2., 3., 4.], [1.]], [[1.], [1.]]],
            [[[1., 2.], [1., 3.]], [[1., 4., 4.], [1., 9., 14.]]])
        p2 = sys2.pole()

        np.testing.assert_array_almost_equal(p2, [-2., -2., -7., -3., -2.])

    def test_double_cancelling_poles_siso(self):

        H = TransferFunction([1, 1], [1, 2, 1])
diff --git a/control/xferfcn.py b/control/xferfcn.py

    def pole(self):
        """Compute the poles of a transfer function."""
 num, den, denorder = self._common_den()
 _, den, denorder = self._common_den(allow_nonproper=True)
        rts = []
        for d, o in zip(den, denorder):
            rts.extend(roots(d[:o + 1]))

        return out

    def _common_den(self, imag_tol=None):
    def _common_den(self, imag_tol=None, allow_nonproper=False):
        """
        Compute MIMO common denominators; return them and adjusted numerators.

            Threshold for the imaginary part of a root to use in detecting
            complex poles

        allow_nonproper : boolean
            Do not enforce proper transfer functions

        Returns
        -------
        num: array
            gives the numerator coefficient array for the ith output and jth
            input; padded for use in td04ad ('C' option); matches the
            denorder order; highest coefficient starts on the left.
            If allow_nonproper=True and the order of a numerator exceeds the
            order of the common denominator, num will be returned as None

        den: array
            sys.inputs by kd
                    dtype=float)
        denorder = zeros((self.inputs,), dtype=int)

        havenonproper = False

        for j in range(self.inputs):
            if not len(poles[j]):
                # no poles matching this input; only one or more gains
                        nwzeros.append(poles[j][ip])

                    numpoly = poleset[i][j][2] * np.atleast_1d(poly(nwzeros))

                    # td04ad expects a proper transfer function. If the
                    # numerater has a higher order than the denominator, the
                    # padding will fail
                    if len(numpoly) > maxindex + 1:
                        if allow_nonproper:
                            havenonproper = True
                            break
                        raise ValueError(
                            self.__str__() +
                            "is not a proper transfer function. "
                            "The degree of the numerators must not exceed "
                            "the degree of the denominators.")

                    # numerator polynomial should be padded on left and right
                    #   ending at maxindex to line up with what td04ad expects.
                    num[i, j, maxindex+1-len(numpoly):maxindex+1] = numpoly
                    # print(num[i, j])

        if havenonproper:
            num = None

        return num, den, denorder

    def sample(self, Ts, method='zoh', alpha=None):
Original file line number	Diff line number	Diff line change
Expand Up		@@ -546,6 +546,26 @@ def test_common_den(self):
		np.zeros((3, 5, 6)))
		np.testing.assert_array_almost_equal(den, denref)

		def test_common_den_nonproper(self):
		""" Test _common_den with order(num)>order(den) """

		tf1 = TransferFunction(
		[[[1., 2., 3.]], [[1., 2.]]],
		[[[1., -2.]], [[1., -3.]]])
		tf2 = TransferFunction(
		[[[1., 2.]], [[1., 2., 3.]]],
		[[[1., -2.]], [[1., -3.]]])

		common_den_ref = np.array([[1., -5., 6.]])

		np.testing.assert_raises(ValueError, tf1._common_den)
		np.testing.assert_raises(ValueError, tf2._common_den)

		_, den1, _ = tf1._common_den(allow_nonproper=True)
		np.testing.assert_array_almost_equal(den1, common_den_ref)
		_, den2, _ = tf2._common_den(allow_nonproper=True)
		np.testing.assert_array_almost_equal(den2, common_den_ref)

		@unittest.skipIf(not slycot_check(), "slycot not installed")
		def test_pole_mimo(self):
		"""Test for correct MIMO poles."""
Expand All		@@ -557,6 +577,14 @@ def test_pole_mimo(self):

		np.testing.assert_array_almost_equal(p, [-2., -2., -7., -3., -2.])

		# non proper transfer function
		sys2 = TransferFunction(
		[[[1., 2., 3., 4.], [1.]], [[1.], [1.]]],
		[[[1., 2.], [1., 3.]], [[1., 4., 4.], [1., 9., 14.]]])
		p2 = sys2.pole()

		np.testing.assert_array_almost_equal(p2, [-2., -2., -7., -3., -2.])

		def test_double_cancelling_poles_siso(self):

		H = TransferFunction([1, 1], [1, 2, 1])
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -679,7 +679,7 @@ def freqresp(self, omega):

		def pole(self):
		"""Compute the poles of a transfer function."""
		num, den, denorder = self._common_den()
		_, den, denorder = self._common_den(allow_nonproper=True)
		rts = []
		for d, o in zip(den, denorder):
		rts.extend(roots(d[:o + 1]))
Expand DownExpand Up		@@ -797,7 +797,7 @@ def returnScipySignalLTI(self):

		return out

		def _common_den(self, imag_tol=None):
		def _common_den(self, imag_tol=None, allow_nonproper=False):
		"""
		Compute MIMO common denominators; return them and adjusted numerators.

Expand All		@@ -813,6 +813,9 @@ def _common_den(self, imag_tol=None):
		Threshold for the imaginary part of a root to use in detecting
		complex poles

		allow_nonproper : boolean
		Do not enforce proper transfer functions

		Returns
		-------
		num: array
Expand All		@@ -822,6 +825,8 @@ def _common_den(self, imag_tol=None):
		gives the numerator coefficient array for the ith output and jth
		input; padded for use in td04ad ('C' option); matches the
		denorder order; highest coefficient starts on the left.
		If allow_nonproper=True and the order of a numerator exceeds the
		order of the common denominator, num will be returned as None

		den: array
		sys.inputs by kd
Expand DownExpand Up		@@ -906,6 +911,8 @@ def _common_den(self, imag_tol=None):
		dtype=float)
		denorder = zeros((self.inputs,), dtype=int)

		havenonproper = False

		for j in range(self.inputs):
		if not len(poles[j]):
		# no poles matching this input; only one or more gains
Expand All		@@ -930,11 +937,28 @@ def _common_den(self, imag_tol=None):
		nwzeros.append(poles[j][ip])

		numpoly = poleset[i][j][2] * np.atleast_1d(poly(nwzeros))

		# td04ad expects a proper transfer function. If the
		# numerater has a higher order than the denominator, the
		# padding will fail
		if len(numpoly) > maxindex + 1:
		if allow_nonproper:
		havenonproper = True
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		break
		raise ValueError(
		self.__str__() +
		"is not a proper transfer function. "
		"The degree of the numerators must not exceed "
		"the degree of the denominators.")

		# numerator polynomial should be padded on left and right
		# ending at maxindex to line up with what td04ad expects.
		num[i, j, maxindex+1-len(numpoly):maxindex+1] = numpoly
		# print(num[i, j])

		if havenonproper:
		num = None

		return num, den, denorder

		def sample(self, Ts, method='zoh', alpha=None):
Expand Down