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[python-control-discuss] SF.net SVN: python-control:[59] branches/control-0.4a/src
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From: <kk...@us...> - 2011-02-08 22:14:38
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Revision: 59
http://python-control.svn.sourceforge.net/python-control/?rev=59&view=rev
Author: kkchen
Date: 2011-02-08 22:14:32 +0000 (Tue, 08 Feb 2011)
Log Message:
-----------
Added xTransferFunction.evalfr and xTransferFunction.freqresp in xferfcn.py.
Also added unit tests for these in TextXferFcn.py.
Kevin K. Chen <kk...@pr...>
Modified Paths:
--------------
branches/control-0.4a/src/TestXferFcn.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 22:14:27 UTC (rev 58)
+++ branches/control-0.4a/src/TestXferFcn.py 2011-02-08 22:14:32 UTC (rev 59)
@@ -306,5 +306,79 @@
np.testing.assert_array_equal(sys4.num, sys3.den)
np.testing.assert_array_equal(sys4.den, sys3.num)
+ # Tests for xTransferFunction.evalfr.
+
+ def testEvalFrSISO(self):
+ """Evaluate the frequency response of a SISO system at one frequency."""
+
+ sys = xTransferFunction([1., 3., 5], [1., 6., 2., -1])
+
+ np.testing.assert_array_almost_equal(sys.evalfr(1.),
+ np.array([[-0.5 - 0.5j]]))
+ np.testing.assert_array_almost_equal(sys.evalfr(32.),
+ np.array([[0.00281959302585077 - 0.030628473607392j]]))
+
+ def testEvalFrMIMO(self):
+ """Evaluate the frequency response of a MIMO system at one frequency."""
+
+ num = [[[1., 2.], [0., 3.], [2., -1.]],
+ [[1.], [4., 0.], [1., -4., 3.]]]
+ den = [[[-3., 2., 4.], [1., 0., 0.], [2., -1.]],
+ [[3., 0., .0], [2., -1., -1.], [1.]]]
+ sys = xTransferFunction(num, den)
+ resp = [[0.147058823529412 + 0.0882352941176471j, -0.75, 1.],
+ [-0.083333333333333, -0.188235294117647 - 0.847058823529412j,
+ -1. - 8.j]]
+
+ np.testing.assert_array_almost_equal(sys.evalfr(2.), resp)
+
+ # Tests for xTransferFunction.freqresp.
+
+ def testFRespSISO(self):
+ """Evaluate the magnitude and phase of a SISO system at multiple
+ frequencies."""
+
+ sys = xTransferFunction([1., 3., 5], [1., 6., 2., -1])
+
+ truemag = [[[4.63507337473906, 0.707106781186548, 0.0866592803995351]]]
+ truephase = [[[-2.89596891081488, -2.35619449019234,
+ -1.32655885133871]]]
+ trueomega = [0.1, 1., 10.]
+
+ mag, phase, omega = sys.freqresp(trueomega)
+
+ np.testing.assert_array_almost_equal(mag, truemag)
+ np.testing.assert_array_almost_equal(phase, truephase)
+ np.testing.assert_array_almost_equal(omega, trueomega)
+
+ def testFRespMIMO(self):
+ """Evaluate the magnitude and phase of a MIMO system at multiple
+ frequencies."""
+
+ num = [[[1., 2.], [0., 3.], [2., -1.]],
+ [[1.], [4., 0.], [1., -4., 3.]]]
+ den = [[[-3., 2., 4.], [1., 0., 0.], [2., -1.]],
+ [[3., 0., .0], [2., -1., -1.], [1.]]]
+ sys = xTransferFunction(num, den)
+
+ trueomega = [0.1, 1., 10.]
+ truemag = [[[0.496287094505259, 0.307147558416976, 0.0334738176210382],
+ [300., 3., 0.03], [1., 1., 1.]],
+ [[33.3333333333333, 0.333333333333333, 0.00333333333333333],
+ [0.390285696125482, 1.26491106406735, 0.198759144198533],
+ [3.01663720059274, 4.47213595499958, 104.92378186093]]]
+ truephase = [[[3.7128711165168e-4, 0.185347949995695, 1.30770596539255],
+ [-np.pi, -np.pi, -np.pi], [0., 0., 0.]],
+ [[-np.pi, -np.pi, -np.pi],
+ [-1.66852323415362, -1.89254688119154, -1.62050658356412],
+ [-0.132989648369409, -1.1071487177940, -2.7504672066207]]]
+
+ mag, phase, omega = sys.freqresp(trueomega)
+
+ np.testing.assert_array_almost_equal(mag, truemag)
+ np.testing.assert_array_almost_equal(phase, truephase)
+ np.testing.assert_array_almost_equal(omega, trueomega)
+
+
if __name__ == "__main__":
- unittest.main()
\ No newline at end of file
+ unittest.main()
Modified: branches/control-0.4a/src/xferfcn.py
===================================================================
--- branches/control-0.4a/src/xferfcn.py 2011-02-08 22:14:27 UTC (rev 58)
+++ branches/control-0.4a/src/xferfcn.py 2011-02-08 22:14:32 UTC (rev 59)
@@ -314,15 +314,37 @@
def evalfr(self, freq):
"""Evaluate a transfer function at a single frequency"""
- # return sp.polyval(self.num, freq*1j) / sp.polyval(self.den, freq*1j)
- pass
+ # Preallocate the output.
+ out = sp.empty((self.outputs, self.inputs), dtype=complex)
+ for i in range(self.outputs):
+ for j in range(self.inputs):
+ out[i][j] = sp.polyval(self.num[i][j], freq * 1.j) / \
+ sp.polyval(self.den[i][j], freq * 1.j)
+
+ return out
+
# Method for generating the frequency response of the system
def freqresp(self, omega):
"""Evaluate a transfer function at a list of frequencies"""
- pass
+ numfreq = len(omega)
+ # Preallocate outputs.
+ mag = sp.empty((self.outputs, self.inputs, numfreq), dtype=complex)
+ phase = sp.empty((self.outputs, self.inputs, numfreq), dtype=complex)
+
+ for i in range(self.outputs):
+ for j in range(self.inputs):
+ fresp = map(lambda w: sp.polyval(self.num[i][j], w * 1.j) / \
+ sp.polyval(self.den[i][j], w * 1.j), omega)
+ fresp = sp.array(fresp)
+
+ mag[i][j] = abs(fresp)
+ phase[i][j] = sp.angle(fresp)
+
+ return mag, phase, omega
+
def poles(self):
"""Compute poles of a transfer function."""
@@ -571,4 +593,4 @@
def ss2tf(sys):
"""Convert a state space object to a transfer function object."""
- pass
\ No newline at end of file
+ pass
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