Revert "Added discrete grid to pzmap function."

Victor · Victor · commit 4117489ec312 · 2018-02-19T12:44:57.000+01:00
This reverts commit dc8410c
diff --git a/control/statesp.py b/control/statesp.py
@@ -460,10 +460,10 @@ def freqresp(self, omega):
         if isdtime(self, strict=True):
             dt = timebase(self)
             cmplx_freqs = exp(1.j * omega * dt)
-            if ((omega * dt).any() > math.pi):
+            if ((omega * dt).any() > pi):
                 warn_message = ("evalfr: frequency evaluation"
                                 " above Nyquist frequency")
-                warn(warn_message)
+                warnings.warn(warn_message)
         else:
             cmplx_freqs = omega * 1.j
 
