allow FRD for feedback()

murrayrm · murrayrm · commit 7e403eac769f · 2014-03-22T18:30:41.000Z
diff --git a/ChangeLog b/ChangeLog
@@ -1,3 +1,7 @@
+2014-03-22  Richard Murray  <murray@sidamo.local>
+
+	* src/bdalg.py (feedback): allow FRD for feedback()
+
 2014-03-22  Richard Murray  <murray@sidamo.local>
 
 	* tests/discrete_test.py (TestDiscrete.test_sample_system): added
diff --git a/src/bdalg.py b/src/bdalg.py
@@ -220,13 +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, frd.FRD)):
+        raise TypeError("sys1 must be a TransferFunction, StateSpace " +
+                        "or FRD 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, frd.FRD)):
+        raise TypeError("sys2 must be a TransferFunction, StateSpace " + 
+                        "or FRD object, or a scalar.")
 
     # If sys1 is a scalar, convert it to the appropriate LTI type so that we can
     # its feedback member function.
