8000 - do not cancel pole/zero pairs before calculating pole() in xferfcn.py · python-control/python-control@7e594c4 · GitHub
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- do not cancel pole/zero pairs before calculating pole() in xferfcn.py
- for the above reason, do conversion on minreal'd xferfcn in statesp.py - add a test for not canceling pole/zero pairs when calculating pole() - add import of matlab in discrete_test.py
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4 files changed

+15
-7
lines changed

4 files changed

+15
-7
lines changed

‎control/statesp.py

Lines changed: 1 addition & 1 deletion
< 8000 td data-grid-cell-id="diff-b5aac033a6dd07653e82d9f5a40afaa775010c2d2d5af8beeb159487b566df72-779-779-1" data-selected="false" role="gridcell" style="background-color:var(--diffBlob-additionNum-bgColor, var(--diffBlob-addition-bgColor-num));text-align:center" tabindex="-1" valign="top" class="focusable-grid-cell diff-line-number position-relative left-side">779
Original file line numberDiff line numberDiff line change
@@ -776,7 +776,7 @@ def _convertToStateSpace(sys, **kw):
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# Change the numerator and denominator arrays so that the transfer
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# function matrix has a common denominator.
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# matrices are also sized/padded to fit td04ad
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num, den, denorder = sys._common_den()
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num, den, denorder = sys.minreal()._common_den()
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# transfer function to state space conversion now should work!
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ssout = td04ad('C', sys.inputs, sys.outputs,

‎control/tests/discrete_test.py

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Original file line numberDiff line numberDiff line change
@@ -6,6 +6,7 @@
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import unittest
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import numpy as np
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from control import *
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from control import matlab
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class TestDiscrete(unittest.TestCase):
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"""Tests for the DiscreteStateSpace class."""

‎control/tests/xferfcn_test.py

Lines changed: 8 additions & 2 deletions
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@@ -427,8 +427,14 @@ def testPoleMIMO(self):
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np.testing.assert_array_almost_equal(p, [-2., -2., -7., -3., -2.])
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# Tests for TransferFunction.feedback.
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@unittest.skipIf(not slycot_check(), "slycot not installed")
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def testDoubleCancelingPoleSiso(self):
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H = TransferFunction([1,1],[1,2,1])
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p = H.pole()
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np.testing.assert_array_almost_equal(p, [-1, -1])
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# Tests for TransferFunction.feedback
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def testFeedbackSISO(self):
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"""Test for correct SISO transfer function feedback."""
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‎control/xferfcn.py

Lines changed: 5 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -752,16 +752,17 @@ def _common_den(self, imag_tol=None):
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# pre-calculate the poles for all num, den
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# has zeros, poles, gain, list for pole indices not in den,
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# number of poles known at the time analyzed
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self2 = self.minreal()
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# do not calculate minreal. Rory's hint .minreal()
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poleset = []
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for i in range(self.outputs):
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poleset.append([])
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for j in range(self.inputs):
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if abs(self2.num[i][j]).max() <= eps:
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if abs(self.num[i][j]).max() <= eps:
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poleset[-1].append( [array([], dtype=float),
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roots(self2.den[i][j]), 0.0, [], 0 ])
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roots(self.den[i][j]), 0.0, [], 0 ])
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else:
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z, p, k = tf2zpk(self2.num[i][j], self2.den[i][j])
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z, p, k = tf2zpk(self.num[i][j], self.den[i][j])
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poleset[-1].append([ z, p, k, [], 0])
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# collect all individual poles

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