From 78b6fc255c5d4708b21960619e66751d47abe8d5 Mon Sep 17 00:00:00 2001 From: choqueuse Date: Tue, 17 Aug 2021 19:22:01 +0200 Subject: [PATCH 1/2] fix the return of the damp method for discrete time systems with a negative real-valued pole --- control/lti.py | 1 + control/tests/lti_test.py | 9 +++++++++ 2 files changed, 10 insertions(+) diff --git a/control/lti.py b/control/lti.py index ef5d5569a..0e53ed5f9 100644 --- a/control/lti.py +++ b/control/lti.py @@ -159,6 +159,7 @@ def damp(self): poles = self.pole() if isdtime(self, strict=True): + poles = poles.astype(complex) splane_poles = np.log(poles)/self.dt else: splane_poles = poles diff --git a/control/tests/lti_test.py b/control/tests/lti_test.py index 9156ecb7e..defcba21e 100644 --- a/control/tests/lti_test.py +++ b/control/tests/lti_test.py @@ -70,6 +70,15 @@ def test_damp(self): np.testing.assert_almost_equal(sys_dt.damp(), expected_dt) np.testing.assert_almost_equal(damp(sys_dt), expected_dt) + #also check that for a discrete system with a negative real pole the damp function can extract wn and theta. + p2_zplane = -0.2 + sys_dt2 = tf(1,[1,-p2_zplane],dt) + wn2, zeta2, _ = sys_dt2.damp() + p2 = -wn2 * zeta2 + 1j * wn2 * np.sqrt(1 - zeta2**2) + p2_zplane = np.exp(p2*dt) + np.testing.assert_almost_equal(sys_dt2.pole(),p2_zplane) + + def test_dcgain(self): sys = tf(84, [1, 2]) np.testing.assert_allclose(sys.dcgain(), 42) From 140ca08fc7ad3dc64b1b5dcb28327ec8647cb205 Mon Sep 17 00:00:00 2001 From: choqueuse Date: Wed, 18 Aug 2021 08:43:42 +0200 Subject: [PATCH 2/2] fix PEP8 compliance style and preserve pole type --- control/lti.py | 3 +-- control/tests/lti_test.py | 13 ++++++------- 2 files changed, 7 insertions(+), 9 deletions(-) diff --git a/control/lti.py b/control/lti.py index 0e53ed5f9..b56c2bb44 100644 --- a/control/lti.py +++ b/control/lti.py @@ -159,8 +159,7 @@ def damp(self): poles = self.pole() if isdtime(self, strict=True): - poles = poles.astype(complex) - splane_poles = np.log(poles)/self.dt + splane_poles = np.log(poles.astype(complex))/self.dt else: splane_poles = poles wn = absolute(splane_poles) diff --git a/control/tests/lti_test.py b/control/tests/lti_test.py index defcba21e..7e4f0ddb4 100644 --- a/control/tests/lti_test.py +++ b/control/tests/lti_test.py @@ -70,15 +70,14 @@ def test_damp(self): np.testing.assert_almost_equal(sys_dt.damp(), expected_dt) np.testing.assert_almost_equal(damp(sys_dt), expected_dt) - #also check that for a discrete system with a negative real pole the damp function can extract wn and theta. + #also check that for a discrete system with a negative real pole the damp function can extract wn and zeta. p2_zplane = -0.2 - sys_dt2 = tf(1,[1,-p2_zplane],dt) - wn2, zeta2, _ = sys_dt2.damp() - p2 = -wn2 * zeta2 + 1j * wn2 * np.sqrt(1 - zeta2**2) - p2_zplane = np.exp(p2*dt) - np.testing.assert_almost_equal(sys_dt2.pole(),p2_zplane) + sys_dt2 = tf(1, [1, -p2_zplane], dt) + wn2, zeta2, p2 = sys_dt2.damp() + p2_splane = -wn2 * zeta2 + 1j * wn2 * np.sqrt(1 - zeta2**2) + p2_zplane = np.exp(p2_splane * dt) + np.testing.assert_almost_equal(p2, p2_zplane) - def test_dcgain(self): sys = tf(84, [1, 2]) np.testing.assert_allclose(sys.dcgain(), 42) pFad - Phonifier reborn

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