Fix minreal not returning a discrete TF

rssalessio · rssalessio · commit d8d6b02a267e · 2017-03-26T17:59:05.000+02:00
diff --git a/control/xferfcn.py b/control/xferfcn.py
@@ -685,7 +685,7 @@ def minreal(self, tol=None):
                 den[i][j] = np.atleast_1d(real(poly(poles)))
 
         # end result
-        return TransferFunction(num, den)
+        return TransferFunction(num, den, None if self.dt == None else self.dt)
 
     def returnScipySignalLTI(self):
         """Return a list of a list of scipy.signal.lti objects.
