fix

nifty5/sugar.py

@@ -260,8 +260,7 @@ _current_module = sys.modules[__name__]
 for f in ["sqrt", "exp", "log", "tanh", "positive_tanh", "conjugate"]:
     def func(f):
         def func2(x):
-            from .linearization import Linearization
-            if isinstance(x, (Field, MultiField, Linearization)):
+            if isinstance(x, (Field, MultiField)):
                 return getattr(x, f)()
             else:
                 return getattr(np, f)(x)