Fixed bug #5 ('dt' instead of 'Ts' in dtime.py) and added some unit tests for dtime and FRD bdalg.

murrayrm · murrayrm · commit 5ce5f57df178 · 2014-03-22T18:09:48.000Z
diff --git a/ChangeLog b/ChangeLog
@@ -1,3 +1,17 @@
+2014-03-22  Richard Murray  <murray@sidamo.local>
+
+	* tests/discrete_test.py (TestDiscrete.test_sample_system): added
+	conversions using tustin and zoh to catch 'dt' bug #5
+
+	* src/dtime.py (sample_system): Changed 'dt' to 'Ts' to fix bug #4
+
+	* tests/frd_test.py (TestFRD.testbdalg): added unit tests for bdalg
+	functions operating on FRD data
+
+	* src/bdalg.py (series, parallel, negate, feedback): updated
+	documentation to note that FRD ovjects work.
+	(feedback): updated conversions to allow for FRD
+
 2013-07-15  Richard Murray  <murray@altura-2.local>
 
 	* src/frdata.py, src/xferfcn.py: updated to use __truediv__ and
diff --git a/src/bdalg.py b/src/bdalg.py
@@ -56,14 +56,15 @@
 import scipy as sp
 import control.xferfcn as tf
 import control.statesp as ss
+import control.frdata as frd
 
 def series(sys1, sys2):
     """Return the series connection sys2 * sys1 for --> sys1 --> sys2 -->.
 
     Parameters
     ----------
-    sys1: scalar, StateSpace, or TransferFunction
-    sys2: scalar, StateSpace, or TransferFunction
+    sys1: scalar, StateSpace, TransferFunction, or FRD
+    sys2: scalar, StateSpace, TransferFunction, or FRD
 
     Returns
     -------
@@ -105,8 +106,8 @@ def parallel(sys1, sys2):
 
     Parameters
     ----------
-    sys1: scalar, StateSpace, or TransferFunction
-    sys2: scalar, StateSpace, or TransferFunction
+    sys1: scalar, StateSpace, TransferFunction, or FRD
+    sys2: scalar, StateSpace, TransferFunction, or FRD
 
     Returns
     -------
@@ -148,7 +149,7 @@ def negate(sys):
 
     Parameters
     ----------
-    sys: StateSpace or TransferFunction
+    sys: StateSpace, TransferFunction or FRD
 
     Returns
     -------
@@ -179,9 +180,9 @@ def feedback(sys1, sys2=1, sign=-1):
 
     Parameters
     ----------
-    sys1: scalar, StateSpace, or TransferFunction
+    sys1: scalar, StateSpace, TransferFunction, FRD
         The primary plant.
-    sys2: scalar, StateSpace, or TransferFunction
+    sys2: scalar, StateSpace, TransferFunction, FRD
         The feedback plant (often a feedback controller).
     sign: scalar 
         The sign of feedback.  `sign` = -1 indicates negative feedback, and
@@ -219,13 +220,13 @@ def feedback(sys1, sys2=1, sign=-1):
 
     # Check for correct input types.
     if not isinstance(sys1, (int, float, complex, tf.TransferFunction,
-        ss.StateSpace)):
-        raise TypeError("sys1 must be a TransferFunction or StateSpace object, \
-or a scalar.")
+                             ss.StateSpace)):
+        raise TypeError("sys1 must be a TransferFunction or StateSpace " +
+                        "object, or a scalar.")
     if not isinstance(sys2, (int, float, complex, tf.TransferFunction,
-        ss.StateSpace)):
-        raise TypeError("sys2 must be a TransferFunction or StateSpace object, \
-or a scalar.")
+                             ss.StateSpace)):
+        raise TypeError("sys2 must be a TransferFunction or StateSpace " + 
+                        "object, or a scalar.")
 
     # If sys1 is a scalar, convert it to the appropriate LTI type so that we can
     # its feedback member function.
@@ -234,6 +235,8 @@ def feedback(sys1, sys2=1, sign=-1):
             sys1 = tf._convertToTransferFunction(sys1)
         elif isinstance(sys2, ss.StateSpace):
             sys1 = ss._convertToStateSpace(sys1)
+        elif isinstance(sys2, frd.FRD):
+            sys1 = ss._convertToFRD(sys1)
         else: # sys2 is a scalar.
             sys1 = tf._convertToTransferFunction(sys1)
             sys2 = tf._convertToTransferFunction(sys2)
diff --git a/src/dtime.py b/src/dtime.py
@@ -112,7 +112,7 @@ def sample_system(sysc, Ts, method='matched'):
             from scipy.signal import cont2discrete
             sys = [sysc.num[0][0], sysc.den[0][0]]
             scipySysD = cont2discrete(sys, Ts, method='bilinear')
-            sysd = TransferFunction(scipySysD[0][0], scipySysD[1], dt)
+            sysd = TransferFunction(scipySysD[0][0], scipySysD[1], Ts)
         except ImportError:
             raise TypeError("cont2discrete not found in scipy.signal; upgrade to v0.10.0+")
         
@@ -121,7 +121,7 @@ def sample_system(sysc, Ts, method='matched'):
             from scipy.signal import cont2discrete
             sys = [sysc.num[0][0], sysc.den[0][0]]
             scipySysD = cont2discrete(sys, Ts, method='zoh')
-            sysd = TransferFunction(scipySysD[0][0],scipySysD[1], dt)
+            sysd = TransferFunction(scipySysD[0][0],scipySysD[1], Ts)
         except ImportError:
             raise TypeError("cont2discrete not found in scipy.signal; upgrade to v0.10.0+")
 
diff --git a/src/frdata.py b/src/frdata.py
@@ -451,7 +451,6 @@ def _convertToFRD(sys, omega, inputs=1, outputs=1):
     """
     
     if isinstance(sys, FRD):
-        
         omega.sort()
         if (abs(omega - sys.omega) < FRD.epsw).all():
             # frequencies match, and system was already frd; simply use
diff --git a/tests/discrete_test.py b/tests/discrete_test.py
@@ -264,6 +264,12 @@ def test_sample_system(self):
         for sysc in (self.siso_ss1, self.siso_ss1c, self.siso_tf1c):
             sysd = sample_system(sysc, 1, method='matched')
             self.assertEqual(sysd.dt, 1)
+
+            sysd = sample_system(sysc, 1, method='tustin')
+            self.assertEqual(sysd.dt, 1)
+
+            sysd = sample_system(sysc, 1, method='zoh')
+            self.assertEqual(sysd.dt, 1)
             # TODO: put in other generic checks
 
         # TODO: check results of converstion
diff --git a/tests/frd_test.py b/tests/frd_test.py
@@ -10,6 +10,7 @@
 from control.xferfcn import TransferFunction
 from control.frdata import FRD, _convertToFRD
 from control.matlab import bode
+import control.bdalg as bdalg
 import control.freqplot
 import matplotlib.pyplot as plt
 
@@ -106,7 +107,43 @@ def testOperatorsTf(self):
             (f1 / h2).freqresp([0.1, 1.0, 10])[1],
             (h1 / h2).freqresp([0.1, 1.0, 10])[1])
         # the reverse does not work
-        
+
+    def testbdalg(self):
+        # get two SISO transfer functions
+        h1 = TransferFunction([1], [1, 2, 2])
+        h2 = TransferFunction([1], [0.1, 1])
+        omega = np.logspace(-1, 2, 10)
+        f1 = FRD(h1, omega)
+        f2 = FRD(h2, omega)
+
+        np.testing.assert_array_almost_equal(
+            (bdalg.series(f1, f2)).freqresp([0.1, 1.0, 10])[0],
+            (bdalg.series(h1, h2)).freqresp([0.1, 1.0, 10])[0])
+
+        np.testing.assert_array_almost_equal(
+            (bdalg.parallel(f1, f2)).freqresp([0.1, 1.0, 10])[0],
+            (bdalg.parallel(h1, h2)).freqresp([0.1, 1.0, 10])[0])
+
+        np.testing.assert_array_almost_equal(
+            (bdalg.feedback(f1, f2)).freqresp([0.1, 1.0, 10])[0],
+            (bdalg.feedback(h1, h2)).freqresp([0.1, 1.0, 10])[0])
+
+        np.testing.assert_array_almost_equal(
+            (bdalg.negate(f1)).freqresp([0.1, 1.0, 10])[0],
+            (bdalg.negate(h1)).freqresp([0.1, 1.0, 10])[0])
+
+#       append() and connect() not implemented for FRD objects
+#        np.testing.assert_array_almost_equal(
+#            (bdalg.append(f1, f2)).freqresp([0.1, 1.0, 10])[0],
+#            (bdalg.append(h1, h2)).freqresp([0.1, 1.0, 10])[0])
+#
+#        f3 = bdalg.append(f1, f2, f2)
+#        h3 = bdalg.append(h1, h2, h2)
+#        Q = np.mat([ [1, 2], [2, -1] ])
+#        np.testing.assert_array_almost_equal(
+#           (bdalg.connect(f3, Q, [2], [1])).freqresp([0.1, 1.0, 10])[0],
+#            (bdalg.connect(h3, Q, [2], [1])).freqresp([0.1, 1.0, 10])[0])
+
     def testFeedback(self):
         h1 = TransferFunction([1], [1, 2, 2])
         omega = np.logspace(-1, 2, 10)
