make frd timebase duplication testing consistent + unit tests

murrayrm · murrayrm · commit 8b29e45d7118 · 2024-11-21T16:28:26.000-08:00
diff --git a/control/frdata.py b/control/frdata.py
@@ -135,10 +135,12 @@ def __init__(self, *args, **kwargs):
         #
         if len(args) == 3:
             # Discrete time transfer function
+            dt = args[-1]
             if 'dt' in kwargs:
-                raise TypeError(
-                    "timebase specified as positional argument and keyword")
-            kwargs['dt'] = args.pop()
+                warn("received multiple dt arguments, "
+                     "using positional arg dt = %s" % dt)
+            kwargs['dt'] = dt
+            args = args[:-1]
 
         if len(args) == 2:
             if not isinstance(args[0], FRD) and isinstance(args[0], LTI):
diff --git a/control/tests/timebase_test.py b/control/tests/timebase_test.py
@@ -119,3 +119,12 @@ def test_composition_override(dt):
 def test_default(fcn, args, kwargs, expected):
     sys = fcn(*args, **kwargs)
     assert sys.dt == expected
+
+    # Some commands allow dt via extra argument
+    if fcn in [ct.ss, ct.tf, ct.zpk, ct.frd] and kwargs.get('dt'):
+        sys = fcn(*args, kwargs['dt'])
+        assert sys.dt == expected
+
+        # Make sure an error is generated if dt is redundant
+        with pytest.warns(UserWarning, match="received multiple dt"):
+            sys = fcn(*args, kwargs['dt'], **kwargs)
