[python-control-discuss] SF.net SVN: python-control:[155] trunk

[<gor...@us...>]

Revision: 155
          http://python-control.svn.sourceforge.net/python-control/?rev=155&view=rev
Author:   goretkin
Date:     2011-04-16 23:45:46 +0000 (Sat, 16 Apr 2011)

Log Message:
-----------
Support for the **,/ operator.
>> s = control.tf.TransferFunction([1, 0],[1])
sys = s/(s**2+s+1) #works as expected

Modified Paths:
--------------
    trunk/setup.py
    trunk/src/xferfcn.py

Modified: trunk/setup.py
===================================================================
--- trunk/setup.py	2011-04-07 20:12:28 UTC (rev 154)
+++ trunk/setup.py	2011-04-16 23:45:46 UTC (rev 155)
@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 
-from distutils.core import setup
+#from distutils.core import setup
+from setuptools import setup
 
 setup(name = 'control',
       version = '0.4c',

Modified: trunk/src/xferfcn.py
===================================================================
--- trunk/src/xferfcn.py	2011-04-07 20:12:28 UTC (rev 154)
+++ trunk/src/xferfcn.py	2011-04-16 23:45:46 UTC (rev 155)
@@ -372,9 +372,13 @@
     def __div__(self, other):
         """Divide two LTI objects."""
         
-        # Convert the second argument to a transfer function.
-        other = _convertToTransferFunction(other)
+        if isinstance(other, (int, float, long, complex)):
+            other = _convertToTransferFunction(other, inputs=self.inputs, 
+                outputs=self.inputs)
+        else:
+            other = _convertToTransferFunction(other)
 
+
         if (self.inputs > 1 or self.outputs > 1 or 
             other.inputs > 1 or other.outputs > 1):
             raise NotImplementedError("TransferFunction.__div__ is currently \
@@ -388,6 +392,11 @@
     # TODO: Division of MIMO transfer function objects is not written yet.
     def __rdiv__(self, other):
         """Right divide two LTI objects."""
+        if isinstance(other, (int, float, long, complex)):
+            other = _convertToTransferFunction(other, inputs=self.inputs, 
+                outputs=self.inputs)
+        else:
+            other = _convertToTransferFunction(other)
         
         if (self.inputs > 1 or self.outputs > 1 or 
             other.inputs > 1 or other.outputs > 1):
@@ -395,6 +404,16 @@
 implemented only for SISO systems.")
 
         return other / self
+    def __pow__(self,other):
+        if not type(other) == int:
+            raise ValueError("Exponent must be an integer")
+        if other == 0:
+            return TransferFunction([1],[1]) #unity
+        if other > 0:
+            return self * (self**(other-1))
+        if other < 0:
+            return (TransferFunction([1],[1]) / self) * (self**(other+1))
+            
         
     def evalfr(self, omega):
         """Evaluate a transfer function at a single angular frequency.


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