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BugFix: tf2ss now handles static gains#129
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -10,6 +10,7 @@ | ||
| # Python 3 compatibility (needs to go here) | ||
| from __future__ import print_function | ||
| from __future__ import division # for _convertToStateSpace | ||
| """Copyright (c) 2010 by California Institute of Technology | ||
| All rights reserved. | ||
| @@ -647,6 +648,7 @@ def _convertToStateSpace(sys, **kw): | ||
| """ | ||
| from .xferfcn import TransferFunction | ||
| import itertools | ||
| if isinstance(sys, StateSpace): | ||
| if len(kw): | ||
| raise TypeError("If sys is a StateSpace, _convertToStateSpace \ | ||
| @@ -679,16 +681,27 @@ def _convertToStateSpace(sys, **kw): | ||
| ssout[3][:sys.outputs, :states], | ||
| ssout[4], sys.dt) | ||
| except ImportError: | ||
| # No Slycot. Scipy tf->ss can't handle MIMO, but static | ||
| # MIMO is an easy special case we can check for here | ||
| maxn = max(max(len(n) for n in nrow) | ||
| for nrow in sys.num) | ||
| maxd = max(max(len(d) for d in drow) | ||
| for drow in sys.den) | ||
| if 1==maxn and 1==maxd: | ||
| D = empty((sys.outputs,sys.inputs),dtype=float) | ||
| for i,j in itertools.product(range(sys.outputs),range(sys.inputs)): | ||
| D[i,j] = sys.num[i][j][0] / sys.den[i][j][0] | ||
| return StateSpace([], [], [], D, sys.dt) | ||
| else: | ||
| if (sys.inputs != 1 or sys.outputs != 1): | ||
| raise TypeError("No support for MIMO without slycot") | ||
| # TODO: do we want to squeeze first and check dimenations? | ||
Member
| ||
| # I think this will fail if num and den aren't 1-D after | ||
| # the squeeze | ||
| lti_sys = lti(squeeze(sys.num), squeeze(sys.den)) | ||
| return StateSpace(lti_sys.A, lti_sys.B, lti_sys.C, lti_sys.D, | ||
| sys.dt) | ||
| elif isinstance(sys, (int, float, complex)): | ||
| if "inputs" in kw: | ||
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -184,6 +184,28 @@ def testConvertMIMO(self): | ||
| if (not slycot_check()): | ||
| self.assertRaises(TypeError, control.tf2ss, tfcn) | ||
| def testTf2ssStaticSiso(self): | ||
| """Regression: tf2ss for SISO static gain""" | ||
| import control | ||
| gsiso = control.tf2ss(control.tf(23, 46)) | ||
| self.assertEqual(0, gsiso.states) | ||
| self.assertEqual(1, gsiso.inputs) | ||
| self.assertEqual(1, gsiso.outputs) | ||
| # in all cases ratios are exactly representable, so assert_array_equal is fine | ||
| np.testing.assert_array_equal([[0.5]], gsiso.D) | ||
| def testTf2ssStaticMimo(self): | ||
| """Regression: tf2ss for MIMO static gain""" | ||
| import control | ||
| # 2x3 TFM | ||
| gmimo = control.tf2ss(control.tf([[ [23], [3], [5] ], [ [-1], [0.125], [101.3] ]], | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others.Learn more. How did you select these coefficients? There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others.Learn more. It's an arbitrary selection of numbers over a (small) range of magnitudes and signs; in all cases the ratios are exactly representable with low precision (see d just below), so I could use np.assert_array_equal(). | ||
| [[ [46], [0.1], [80] ], [ [2], [-0.1], [1] ]])) | ||
| self.assertEqual(0, gmimo.states) | ||
| self.assertEqual(3, gmimo.inputs) | ||
| self.assertEqual(2, gmimo.outputs) | ||
| d = np.matrix([[0.5, 30, 0.0625], [-0.5, -1.25, 101.3]]) | ||
| np.testing.assert_array_equal(d, gmimo.D) | ||
| def suite(): | ||
| return unittest.TestLoader().loadTestsFromTestCase(TestConvert) | ||