make sure transform is float-typed

masque/library.py

@@ -455,7 +455,7 @@ class ILibraryView(Mapping[str, 'Pattern'], metaclass=ABCMeta):
         if transform is None or transform is True:
             transform = numpy.zeros(4)
         elif transform is not False:
-            transform = numpy.array(transform)
+            transform = numpy.array(transform, dtype=float, copy=False)
 
         original_pattern = pattern