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[python-control-discuss] SF.net SVN: python-control:[82] branches/control-0.4a/src
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From: <kk...@us...> - 2011-02-08 22:16:32
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Revision: 82
http://python-control.svn.sourceforge.net/python-control/?rev=82&view=rev
Author: kkchen
Date: 2011-02-08 22:16:26 +0000 (Tue, 08 Feb 2011)
Log Message:
-----------
Implemented and tested convertToTransferFunction (which ss2tf uses).
Various fixes:
- changed control.exception to exception in the imports of statefbk.py
- changed sys + (const) to behave more like MATLAB
Kevin K. Chen <kk...@pr...>
Modified Paths:
--------------
branches/control-0.4a/src/TestXferFcn.py
branches/control-0.4a/src/statefbk.py
branches/control-0.4a/src/statesp.py
branches/control-0.4a/src/xferfcn.py
Modified: branches/control-0.4a/src/TestXferFcn.py
===================================================================
--- branches/control-0.4a/src/TestXferFcn.py 2011-02-08 22:16:21 UTC (rev 81)
+++ branches/control-0.4a/src/TestXferFcn.py 2011-02-08 22:16:26 UTC (rev 82)
@@ -1,7 +1,8 @@
#!/usr/bin/env python
import numpy as np
-from xferfcn import TransferFunction
+from statesp import StateSpace
+from xferfcn import TransferFunction, convertToTransferFunction
import unittest
class TestXferFcn(unittest.TestCase):
@@ -383,7 +384,8 @@
# Tests for TransferFunction.feedback.
def testFeedbackSISO(self):
-
+ """Test for correct SISO transfer function feedback."""
+
sys1 = TransferFunction([-1., 4.], [1., 3., 5.])
sys2 = TransferFunction([2., 3., 0.], [1., -3., 4., 0])
@@ -395,5 +397,27 @@
np.testing.assert_array_equal(sys4.num, [[[-1., 7., -16., 16., 0.]]])
np.testing.assert_array_equal(sys4.den, [[[1., 0., 2., -8., 8., 0.]]])
+ def testConvertToTransferFunction(self):
+ """Test for correct state space to transfer function conversion."""
+
+ A = [[1., -2.], [-3., 4.]]
+ B = [[6., 5.], [4., 3.]]
+ C = [[1., -2.], [3., -4.], [5., -6.]]
+ D = [[1., 0.], [0., 1.], [1., 0.]]
+ sys = StateSpace(A, B, C, D)
+
+ tfsys = convertToTransferFunction(sys)
+
+ num = [[np.array([1., -7., 10.]), np.array([-1., 10.])],
+ [np.array([2., -8.]), np.array([1., -2., -8.])],
+ [np.array([1., 1., -30.]), np.array([7., -22.])]]
+ den = [[np.array([1., -5., -2.]) for j in range(sys.inputs)]
+ for i in range(sys.outputs)]
+
+ for i in range(sys.outputs):
+ for j in range(sys.inputs):
+ np.testing.assert_array_almost_equal(tfsys.num[i][j], num[i][j])
+ np.testing.assert_array_almost_equal(tfsys.den[i][j], den[i][j])
+
if __name__ == "__main__":
unittest.main()
Modified: branches/control-0.4a/src/statefbk.py
===================================================================
--- branches/control-0.4a/src/statefbk.py 2011-02-08 22:16:21 UTC (rev 81)
+++ branches/control-0.4a/src/statefbk.py 2011-02-08 22:16:26 UTC (rev 82)
@@ -42,7 +42,7 @@
# External packages and modules
import numpy as np
import ctrlutil
-from control.exception import *
+from exception import *
# Pole placement
def place(A, B, p):
Modified: branches/control-0.4a/src/statesp.py
===================================================================
--- branches/control-0.4a/src/statesp.py 2011-02-08 22:16:21 UTC (rev 81)
+++ branches/control-0.4a/src/statesp.py 2011-02-08 22:16:26 UTC (rev 82)
@@ -69,7 +69,7 @@
"""
from numpy import angle, any, array, concatenate, cos, dot, empty, exp, eye, \
- pi, poly, poly1d, matrix, roots, sin, zeros
+ ones, pi, poly, poly1d, matrix, roots, sin, zeros
from numpy.random import rand, randn
from numpy.linalg import inv, det, solve
from numpy.linalg.linalg import LinAlgError
@@ -382,7 +382,7 @@
# The following Doesn't work due to inconsistencies in ltisys:
# return StateSpace([[]], [[]], [[]], eye(outputs, inputs))
return StateSpace(0., zeros((1, inputs)), zeros((outputs, 1)),
- sys * eye(outputs, inputs))
+ sys * ones(outputs, inputs))
else:
raise TypeError("Can't convert given type to StateSpace system.")
Modified: branches/control-0.4a/src/xferfcn.py
===================================================================
--- branches/control-0.4a/src/xferfcn.py 2011-02-08 22:16:21 UTC (rev 81)
+++ branches/control-0.4a/src/xferfcn.py 2011-02-08 22:16:26 UTC (rev 82)
@@ -75,6 +75,7 @@
polyval, zeros
from scipy.signal import lti
from copy import deepcopy
+from slycot import tb04ad
from lti import Lti
import statesp
@@ -397,8 +398,8 @@
polyval(self.den[i][j], w * 1.j)), omega)
fresp = array(fresp)
- mag[i, j] = abs(fresp)
- phase[i, j] = angle(fresp)
+ mag[i, j, :] = abs(fresp)
+ phase[i, j, :] = angle(fresp)
return mag, phase, omega
@@ -537,15 +538,24 @@
if isinstance(sys, TransferFunction):
return sys
elif isinstance(sys, statesp.StateSpace):
- # TODO: Wrap SLICOT to do state space to transfer function conversion.
- raise NotImplementedError("State space to transfer function conversion \
-is not implemented yet.")
+ # Use Slycot to make the transformation.
+ tfout = tb04ad(sys.states, sys.inputs, sys.outputs, sys.A, sys.B, sys.C,
+ sys.D, sys.outputs, sys.outputs, sys.inputs)
+
+ # Preallocate outputs.
+ num = [[[] for j in range(sys.inputs)] for i in range(sys.outputs)]
+ den = [[[] for j in range(sys.inputs)] for i in range(sys.outputs)]
+
+ for i in range(sys.outputs):
+ for j in range(sys.inputs):
+ num[i][j] = list(tfout[6][i, j, :])
+ # Each transfer function matrix row has a common denominator.
+ den[i][j] = list(tfout[5][i, :])
+
+ return TransferFunction(num, den)
elif isinstance(sys, (int, long, float, complex)):
- # Make an identity system.
- num = [[[0] for j in range(inputs)] for i in range(outputs)]
+ num = [[[sys] for j in range(inputs)] for i in range(outputs)]
den = [[[1] for j in range(inputs)] for i in range(outputs)]
- for i in range(min(inputs, outputs)):
- num[i][i] = [sys]
return TransferFunction(num, den)
else:
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