add comment to Hermite::LocalValuedFunction

dune/functions/functionspacebases/hermitebasis.hh

@@ -82,9 +82,10 @@ namespace Dune
 
           friend auto derivative(LocalValuedFunction const &t)
           {
-            return LocalValuedFunction<std::decay<decltype(derivative(t.f_))::type>, LocalCoordinate, Element>(derivative(t.f_), element_);
-            // auto df = derivative(t.f_);
-            // return LocalValuedFunction<typename std::decay<decltype(df)>::type, LocalCoordinate, Element>(df, t.element_);
+            // I would like to do this
+            // return LocalValuedFunction<typename std::decay<decltype(derivative(t.f_))>::type, LocalCoordinate, Element>(derivative(t.f_), t.element_);
+            // But it leads to a DifferentiableFunction which causes a segmentation violation when calling asInterface() ....
+            return derivative(t.f_);
           }
         };
       };