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fix issue with slycot balred change in state #762

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Aug 20, 2022
Merged

fix issue with slycot balred change in state #762

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48 changes: 40 additions & 8 deletions control/tests/modelsimp_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -182,17 +182,33 @@ def testBalredTruncate(self, matarrayin):
B = matarrayin([[2.], [0.], [0.], [0.]])
C = matarrayin([[0.5, 0.6875, 0.7031, 0.5]])
D = matarrayin([[0.]])

sys = StateSpace(A, B, C, D)
orders = 2
rsys = balred(sys, orders, method='truncate')
Ar, Br, Cr, Dr = rsys.A, rsys.B, rsys.C, rsys.D

# Result from MATLAB
Artrue = np.array([[-1.958, -1.194], [-1.194, -0.8344]])
Brtrue = np.array([[0.9057], [0.4068]])
Crtrue = np.array([[0.9057, 0.4068]])
Drtrue = np.array([[0.]])
np.testing.assert_array_almost_equal(rsys.A, Artrue, decimal=2)
np.testing.assert_array_almost_equal(rsys.B, Brtrue, decimal=4)
np.testing.assert_array_almost_equal(rsys.C, Crtrue, decimal=4)
np.testing.assert_array_almost_equal(rsys.D, Drtrue, decimal=4)

# Look for possible changes in state in slycot
T1 = np.array([[1, 0], [0, -1]])
T2 = np.array([[-1, 0], [0, 1]])
T3 = np.array([[0, 1], [1, 0]])
for T in (T1, T2, T3):
if np.allclose(T @ Ar @ T, Artrue, atol=1e-2, rtol=1e-2):
# Apply a similarity transformation
Ar, Br, Cr = T @ Ar @ T, T @ Br, Cr @ T
break

# Make sure we got the correct answer
np.testing.assert_array_almost_equal(Ar, Artrue, decimal=2)
np.testing.assert_array_almost_equal(Br, Brtrue, decimal=4)
np.testing.assert_array_almost_equal(Cr, Crtrue, decimal=4)
np.testing.assert_array_almost_equal(Dr, Drtrue, decimal=4)

@slycotonly
def testBalredMatchDC(self, matarrayin):
Expand All @@ -207,16 +223,32 @@ def testBalredMatchDC(self, matarrayin):
B = matarrayin([[2.], [0.], [0.], [0.]])
C = matarrayin([[0.5, 0.6875, 0.7031, 0.5]])
D = matarrayin([[0.]])

sys = StateSpace(A, B, C, D)
orders = 2
rsys = balred(sys,orders,method='matchdc')
Ar, Br, Cr, Dr = rsys.A, rsys.B, rsys.C, rsys.D

# Result from MATLAB
Artrue = np.array(
[[-4.43094773, -4.55232904],
[-4.55232904, -5.36195206]])
Brtrue = np.array([[1.36235673], [1.03114388]])
Crtrue = np.array([[1.36235673, 1.03114388]])
Drtrue = np.array([[-0.08383902]])
np.testing.assert_array_almost_equal(rsys.A, Artrue, decimal=2)
np.testing.assert_array_almost_equal(rsys.B, Brtrue, decimal=4)
np.testing.assert_array_almost_equal(rsys.C, Crtrue, decimal=4)
np.testing.assert_array_almost_equal(rsys.D, Drtrue, decimal=4)

# Look for possible changes in state in slycot
T1 = np.array([[1, 0], [0, -1]])
T2 = np.array([[-1, 0], [0, 1]])
T3 = np.array([[0, 1], [1, 0]])
for T in (T1, T2, T3):
if np.allclose(T @ Ar @ T, Artrue, atol=1e-2, rtol=1e-2):
# Apply a similarity transformation
Ar, Br, Cr = T @ Ar @ T, T @ Br, Cr @ T
break

# Make sure we got the correct answer
np.testing.assert_array_almost_equal(Ar, Artrue, decimal=2)
np.testing.assert_array_almost_equal(Br, Brtrue, decimal=4)
np.testing.assert_array_almost_equal(Cr, Crtrue, decimal=4)
np.testing.assert_array_almost_equal(Dr, Drtrue, decimal=4)