Correct detection of continuous-time systems

roryyorke · roryyorke · commit 514e32318c86 · 2022-04-27T07:09:41.000+02:00
diff --git a/control/statesp.py b/control/statesp.py
@@ -1941,9 +1941,7 @@ def linfnorm(sys, tol=1e-10):
         fpeak = 0
         return gpeak, fpeak
 
-    if sys.dt is None:
-        raise ValueError('unspecified time base')
-    dico = 'C' if sys.dt==0 else 'D'
+    dico = 'C' if sys.isctime() else 'D'
     jobe = 'I'
     equil = 'S'
     jobd = 'Z' if all(0 == d.flat) else 'D'
