freqresp now sorts omega, to be more like MATLAB.

Kevin Chen · Kevin Chen · commit 05c24a222259 · 2011-02-08T22:17:13.000Z
Kevin K. Chen &lt;kkchen@princeton.edu&gt;
diff --git a/src/matlab.py b/src/matlab.py
@@ -646,7 +646,7 @@ def freqresp(sys, omega):
     Parameters
     ----------
     sys: StateSpace or TransferFunction object
-    omega: list, tuple, or ndarray
+    omega: list or ndarray
 
     Returns
     -------
@@ -662,7 +662,8 @@ def freqresp(sys, omega):
     Notes
     -----
     This function is a wrapper for StateSpace.freqresp and
-    TransferFunction.freqresp.
+    TransferFunction.freqresp.  The output omega is a sorted version of the
+    input omega.
 
     Examples
     --------
diff --git a/src/statesp.py b/src/statesp.py
@@ -301,7 +301,8 @@ def freqresp(self, omega):
 
         reports the value of the magnitude, phase, and angular frequency of the
         system's transfer function matrix evaluated at s = i * omega, where
-        omega is a list of angular frequencies.
+        omega is a list of angular frequencies, and is a sorted version of the
+        input omega.
 
         """
         
@@ -311,6 +312,8 @@ def freqresp(self, omega):
         phase = empty((self.outputs, self.inputs, numfreq))
         fresp = empty((self.outputs, self.inputs, numfreq), dtype=complex)
 
+        omega.sort()
+
         for k in range(numfreq):
             fresp[:, :, k] = self.evalfr(omega[k])
 
diff --git a/src/xferfcn.py b/src/xferfcn.py
@@ -386,7 +386,7 @@ def freqresp(self, omega):
 
         reports the value of the magnitude, phase, and angular frequency of the 
         transfer function matrix evaluated at s = i * omega, where omega is a
-        list of angular frequencies.
+        list of angular frequencies, and is a sorted version of the input omega.
 
         """
         
@@ -395,6 +395,8 @@ def freqresp(self, omega):
         mag = empty((self.outputs, self.inputs, numfreq))
         phase = empty((self.outputs, self.inputs, numfreq))
 
+        omega.sort()
+
         for i in range(self.outputs):
             for j in range(self.inputs):
                 fresp = map(lambda w: (polyval(self.num[i][j], w * 1.j) / 
