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Allow minreal to work with static gain StateSpace objects #108

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e8ee43f
BugFix?: allow straightforward creation of static gain StateSpace obj…
roryyorke Aug 11, 2016
7382644
BugFix: fix Python 2.7 failure.
roryyorke Aug 11, 2016
2794260
MessageFix: remove extra 'C'
roryyorke Aug 12, 2016
fb1e905
BugFix: allow minreal on static gain StateSpace objects
roryyorke Aug 12, 2016
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BugFix: allow minreal on static gain StateSpace objects 
Do this by only calling Slycot's tb01pd for non-static systems.
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@roryyorke
roryyorke committed Aug 12, 2016
commit fb1e90510b99cefa788a5a40bf5c71cc192fa0ec
28 changes: 16 additions & 12 deletions control/statesp.py
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Original file line number Diff line number Diff line change
Expand Up @@ -471,18 +471,22 @@ def feedback(self, other=1, sign=-1):
def minreal(self, tol=0.0):
"""Calculate a minimal realization, removes unobservable and
uncontrollable states"""
try:
from slycot import tb01pd
B = empty((self.states, max(self.inputs, self.outputs)))
B[:,:self.inputs] = self.B
C = empty((max(self.outputs, self.inputs), self.states))
C[:self.outputs,:] = self.C
A, B, C, nr = tb01pd(self.states, self.inputs, self.outputs,
self.A, B, C, tol=tol)
return StateSpace(A[:nr,:nr], B[:nr,:self.inputs],
C[:self.outputs,:nr], self.D)
except ImportError:
raise TypeError("minreal requires slycot tb01pd")
if self.states:
try:
from slycot import tb01pd
B = empty((self.states, max(self.inputs, self.outputs)))
B[:,:self.inputs] = self.B
C = empty((max(self.outputs, self.inputs), self.states))
C[:self.outputs,:] = self.C
A, B, C, nr = tb01pd(self.states, self.inputs, self.outputs,
self.A, B, C, tol=tol)
return StateSpace(A[:nr,:nr], B[:nr,:self.inputs],
C[:self.outputs,:nr], self.D)
except ImportError:
raise TypeError("minreal requires slycot tb01pd")
else:
return StateSpace(self)


# TODO: add discrete time check
def returnScipySignalLTI(self):
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11 changes: 11 additions & 0 deletions control/tests/statesp_test.py
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Expand Up @@ -297,6 +297,17 @@ def test_BadEmptyMatrices(self):
self.assertRaises(ValueError,StateSpace, [], [], [1], [1])
self.assertRaises(ValueError,StateSpace, [1], [1], [1], [])


def test_minrealStaticGain(self):
"""Regression: minreal on static gain was failing"""
g1 = StateSpace([],[],[],[1])
g2 = g1.minreal()
np.testing.assert_array_equal(g1.A, g2.A)
np.testing.assert_array_equal(g1.B, g2.B)
np.testing.assert_array_equal(g1.C, g2.C)
np.testing.assert_array_equal(g1.D, g2.D)


class TestRss(unittest.TestCase):
"""These are tests for the proper functionality of statesp.rss."""

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