Check eigenvalues' real part using NumPy

mp4096 · mp4096 · commit 020f64c10dce · 2016-08-25T10:27:38.000+02:00
Faster than converting to a pure Python list.
diff --git a/control/modelsimp.py b/control/modelsimp.py
@@ -149,7 +149,7 @@ def modred(sys, ELIM, method='matchdc'):
 
 
     #Check system is stable
-    if any(e.real >= 0.0 for e in np.linalg.eigvals(sys.A)):
+    if np.any(np.linalg.eigvals(sys.A).real >= 0.0):
         raise ValueError("Oops, the system is unstable!")
 
     ELIM = np.sort(ELIM)
@@ -251,7 +251,7 @@ def balred(sys, orders, method='truncate'):
     dico = 'C'
 
     #Check system is stable
-    if any(e.real >= 0.0 for e in np.linalg.eigvals(sys.A)):
+    if np.any(np.linalg.eigvals(sys.A).real >= 0.0):
         raise ValueError("Oops, the system is unstable!")
 
     if method=='matchdc':
diff --git a/control/statefbk.py b/control/statefbk.py
@@ -355,7 +355,7 @@ def gram(sys,type):
 
     #TODO: Check system is stable, perhaps a utility in ctrlutil.py
         # or a method of the StateSpace class?
-    if any(e.real >= 0.0 for e in np.linalg.eigvals(sys.A)):
+    if np.any(np.linalg.eigvals(sys.A).real >= 0.0):
         raise ValueError("Oops, the system is unstable!")
 
     if type=='c':
