added keyword arguments to xferfcn.tf and statesp.ss to set dt

sawyerbfuller · sawyerbfuller · commit 2bd912d03fda · 2020-07-22T13:42:10.000-07:00
diff --git a/control/statesp.py b/control/statesp.py
@@ -226,7 +226,7 @@ def __init__(self, *args, **kwargs):
         elif len(args) == 5:
             dt = args[4]
             if 'dt' in kwargs:
-                warn('received multiple dt arguments, using positional arg'%dt)
+                warn('received multiple dt arguments, using positional arg dt=%s'%dt)
         elif len(args) == 1:
             try:
                 dt = args[0].dt
@@ -1243,7 +1243,7 @@ def _mimo2simo(sys, input, warn_conversion=False):
 
     return sys
 
-def ss(*args):
+def ss(*args, **kwargs):
     """ss(A, B, C, D[, dt])
 
     Create a state space system.
@@ -1319,7 +1319,7 @@ def ss(*args):
     """
 
     if len(args) == 4 or len(args) == 5:
-        return StateSpace(*args)
+        return StateSpace(*args, **kwargs)
     elif len(args) == 1:
         from .xferfcn import TransferFunction
         sys = args[0]
@@ -1331,7 +1331,7 @@ def ss(*args):
             raise TypeError("ss(sys): sys must be a StateSpace or \
 TransferFunction object.  It is %s." % type(sys))
     else:
-        raise ValueError("Needs 1 or 4 arguments; received %i." % len(args))
+        raise ValueError("Needs 1, 4, or 5 arguments; received %i." % len(args))
 
 
 def tf2ss(*args):
diff --git a/control/xferfcn.py b/control/xferfcn.py
@@ -217,7 +217,7 @@ def __init__(self, *args, **kwargs):
         elif len(args) == 3:
             # Discrete time transfer function
             if 'dt' in kwargs:
-                warn('received multiple dt arguments, using positional arg'%dt)
+                warn('received multiple dt arguments, using positional arg dt=%s'%dt)
         elif len(args) == 1:
             # TODO: not sure this can ever happen since dt is always present
             try:
@@ -1301,7 +1301,7 @@ def _convert_to_transfer_function(sys, **kw):
     raise TypeError("Can't convert given type to TransferFunction system.")
 
 
-def tf(*args):
+def tf(*args, **kwargs):
     """tf(num, den[, dt])
 
     Create a transfer function system. Can create MIMO systems.
@@ -1391,7 +1391,7 @@ def tf(*args):
     """
 
     if len(args) == 2 or len(args) == 3:
-        return TransferFunction(*args)
+        return TransferFunction(*args, **kwargs)
     elif len(args) == 1:
         # Look for special cases defining differential/delay operator
         if args[0] == 's':
@@ -1412,7 +1412,7 @@ def tf(*args):
         raise ValueError("Needs 1 or 2 arguments; received %i." % len(args))
 
 
-def ss2tf(*args):
+def ss2tf(*args, **kwargs):
     """ss2tf(sys)
 
     Transform a state space system to a transfer function.
@@ -1477,7 +1477,7 @@ def ss2tf(*args):
     from .statesp import StateSpace
     if len(args) == 4 or len(args) == 5:
         # Assume we were given the A, B, C, D matrix and (optional) dt
-        return _convert_to_transfer_function(StateSpace(*args))
+        return _convert_to_transfer_function(StateSpace(*args, **kwargs))
 
     elif len(args) == 1:
         sys = args[0]
