Add child() function to DiscreteFunction

src/amdis/gridfunctions/DiscreteFunction.hpp

@@ -151,6 +151,13 @@ namespace AMDiS
       return *dofVector_;
     }
 
+    template <class TreePath = RootTreePath>
+    auto child(TreePath const& path = {}) const
+    {
+      auto&& tp = makeTreePath(path);
+      return makeDiscreteFunction(*dofVector_, cat(this->treePath_,tp));
+    }
+
   protected:
     DOFVector<GB,VT> const* dofVector_;
     TreePath treePath_;
@@ -234,6 +241,15 @@ namespace AMDiS
     /// Return the const DOFVector
     using Super::coefficients;
 
+    template <class TreePath = RootTreePath>
+    auto child(TreePath const& path = {})
+    {
+      auto&& tp = makeTreePath(path);
+      return makeDiscreteFunction(*mutableDofVector_, cat(this->treePath_,tp));
+    }
+
+    using Super::child;
+
   protected:
     DOFVector<GB,VT>* mutableDofVector_;
   };

src/amdis/gridfunctions/DiscreteLocalFunction.inc.hpp

@@ -28,14 +28,14 @@ public:
   LocalFunction(DiscreteFunction const& globalFunction)
     : globalFunction_(globalFunction)
     , localView_(globalFunction_.basis()->localView())
-    , subTree_(&child(localView_.tree(), globalFunction_.treePath()))
+    , subTree_(&Dune::TypeTree::child(localView_.tree(), globalFunction_.treePath()))
   {}
 
   /// Copy constructor.
   LocalFunction(LocalFunction const& other)
     : globalFunction_(other.globalFunction_)
     , localView_(globalFunction_.basis()->localView())
-    , subTree_(&child(localView_.tree(), globalFunction_.treePath()))
+    , subTree_(&Dune::TypeTree::child(localView_.tree(), globalFunction_.treePath()))
   {}
 
   /// \brief Bind the LocalView to the element
@@ -157,7 +157,7 @@ public:
     : globalFunction_(globalFunction)
     , type_(type)
     , localView_(globalFunction_.basis()->localView())
-    , subTree_(&child(localView_.tree(), globalFunction_.treePath()))
+    , subTree_(&Dune::TypeTree::child(localView_.tree(), globalFunction_.treePath()))
   {}
 
   /// Copy constructor.
@@ -165,7 +165,7 @@ public:
     : globalFunction_(other.globalFunction_)
     , type_(other.type_)
     , localView_(globalFunction_.basis()->localView())
-    , subTree_(&child(localView_.tree(), globalFunction_.treePath()))
+    , subTree_(&Dune::TypeTree::child(localView_.tree(), globalFunction_.treePath()))
   {}
 
   void bind(Element const& element)

src/amdis/io/DuneVtkWriter.hpp

@@ -22,10 +22,11 @@ namespace AMDiS
     using GridView = typename GB::GridView;
     using Writer = Dune::VtkWriter<GridView>;
     using SeqWriter = Dune::PvdWriter<Writer>;
+    using Function = DiscreteFunction<GB,VT,TP,true>;
 
   public:
     /// Constructor.
-    DuneVtkWriter(std::string const& name, DiscreteFunction<GB,VT,TP> const& discreteFct)
+    DuneVtkWriter(std::string const& name, Function const& discreteFct)
       : FileWriterBase(name)
       , discreteFct_(discreteFct)
     {
@@ -75,7 +76,7 @@ namespace AMDiS
     }
 
   private:
-    DiscreteFunction<GB,VT,TP> discreteFct_;
+    Function discreteFct_;
 
     std::shared_ptr<Writer> vtkWriter_;
     std::shared_ptr<SeqWriter> vtkSeqWriter_;

test/DiscreteFunctionTest.cpp

@@ -69,6 +69,13 @@ int main(int argc, char** argv)
   auto u1_c = makeDiscreteFunction(U_c);
   auto u1_m = makeDiscreteFunction(U_m);
 
+  // sub-range view on DiscreteFunction
+  auto su1_c = u1_c.child();
+  auto su1_c0 = u1_c.child(0);
+
+  auto su1_m = u1_m.child();
+  auto su1_m0 = u1_m.child(0);
+
   using Range = typename decltype(u0)::Range;
 
   auto expr1 = [](auto const& x) {