update LinearIOSystem.__rmul__ for Python2/Python3 consistency

murrayrm · murrayrm · commit 08b1c2a0fd55 · 2021-01-05T07:37:42.000-08:00
diff --git a/control/iosys.py b/control/iosys.py
@@ -254,20 +254,24 @@ def __mul__(sys2, sys1):
 
     def __rmul__(sys1, sys2):
         """Pre-multiply an input/output systems by a scalar/matrix"""
-        if isinstance(sys2, (int, float, np.number)):
+        if isinstance(sys2, InputOutputSystem):
+            # Both systems are InputOutputSystems => use __mul__
+            return InputOutputSystem.__mul__(sys2, sys1)
+
+        elif isinstance(sys2, (int, float, np.number)):
             # TODO: Scale the output
             raise NotImplemented("Scalar multiplication not yet implemented")
 
         elif isinstance(sys2, np.ndarray):
             # TODO: Post-multiply by a matrix
             raise NotImplemented("Matrix multiplication not yet implemented")
 
-        elif not isinstance(sys2, InputOutputSystem):
-            raise TypeError("Unknown I/O system object ", sys1)
+        elif isinstance(sys2, StateSpace):
+            # TODO: Should eventuall preserve LinearIOSystem structure
+            return StateSpace.__mul__(sys2, sys1)
 
         else:
-            # Both systems are InputOutputSystems => use __mul__
-            return InputOutputSystem.__mul__(sys2, sys1)
+            raise TypeError("Unknown I/O system object ", sys1)
 
     def __add__(sys1, sys2):
         """Add two input/output systems (parallel interconnection)"""
diff --git a/control/tests/type_conversion_test.py b/control/tests/type_conversion_test.py
@@ -72,7 +72,7 @@ def sys_dict():
     ('sub',     'flt', ['ss',  'tf',  'xrd', 'xio', 'xos', 'arr', 'flt']),
     
     # op        left     ss     tf    frd    lio    ios    arr    flt
-    ('mul',     'ss',  ['ss',  'ss',  'xrd', 'xio', 'xos', 'ss',  'ss' ]),
+    ('mul',     'ss',  ['ss',  'ss',  'xrd', 'ss',  'xos', 'ss',  'ss' ]),
     ('mul',     'tf',  ['tf',  'tf',  'xrd', 'tf',  'xos', 'tf',  'tf' ]),
     ('mul',     'frd', ['xrd', 'xrd', 'frd', 'xrd', 'E',   'xrd', 'frd']),
     ('mul',     'lio', ['xio', 'xio', 'xrd', 'lio', 'ios', 'xio', 'xio']),
