Merge pull request #680 from bnavigator/vector-frd-feedback

murrayrm · web-flow · commit 2ce4bbd983ce · 2021-12-26T06:58:21.000-08:00
vectorize FRD feedback function
diff --git a/control/frdata.py b/control/frdata.py
@@ -535,16 +535,15 @@ def feedback(self, other=1, sign=-1):
         if (self.noutputs != other.ninputs or self.ninputs != other.noutputs):
             raise ValueError(
                 "FRD.feedback, inputs/outputs mismatch")
-        fresp = empty((self.noutputs, self.ninputs, len(other.omega)),
-                      dtype=complex)
-        # TODO: vectorize this
+
         # TODO: handle omega re-mapping
-        # TODO: is there a reason to use linalg.solve instead of linalg.inv?
-        # https://github.com/python-control/python-control/pull/314#discussion_r294075154
-        for k, w in enumerate(other.omega):
-            fresp[:, :, k] = self.fresp[:, :, k] @ linalg.solve(
-                eye(self.ninputs) + other.fresp[:, :, k] @ self.fresp[:, :, k],
-                eye(self.ninputs))
+
+        # reorder array axes in order to leverage numpy broadcasting
+        myfresp = np.moveaxis(self.fresp, 2, 0)
+        otherfresp = np.moveaxis(other.fresp, 2, 0)
+        I_AB = eye(self.ninputs)[np.newaxis, :, :] + otherfresp @ myfresp
+        resfresp = (myfresp @ linalg.inv(I_AB))
+        fresp = np.moveaxis(resfresp, 0, 2)
 
         return FRD(fresp, other.omega, smooth=(self.ifunc is not None))
 
