[examples] Fix matrix/vector types of examples

The nested matrix and vector types should correspond to the index tree of the basis. Here, this is not the case since Field*<T,*> was used instead of T. While this is in many cases no problem, it may fail if the matrix is recursively traversed with IsNumber as termination criterion.

examples/poisson-mfem.cc

@@ -101,9 +101,9 @@ int main (int argc, char *argv[])
   //   Stiffness matrix and right hand side vector
   /////////////////////////////////////////////////////////
 
-  using Matrix = Dune::Matrix<Dune::BCRSMatrix<Dune::FieldMatrix<double,1,1> > >;
-  using Vector = Dune::BlockVector<Dune::BlockVector<Dune::FieldVector<double,1> > >;
-  using BitVector = Dune::BlockVector<Dune::BlockVector<Dune::FieldVector<char,1> > >;
+  using Matrix = Dune::Matrix<Dune::BCRSMatrix<double> >;
+  using Vector = Dune::BlockVector<Dune::BlockVector<double> >;
+  using BitVector = Dune::BlockVector<Dune::BlockVector<char> >;
 
   using Functions::istlVectorBackend;