diff --git a/dune.module b/dune.module
index 58ea718f31ce5cf7c3a772768e36fafcfc563de1..57f4d63a71c28d3e24d78b28e92466da3d288893 100644
--- a/dune.module
+++ b/dune.module
@@ -7,4 +7,4 @@ Module: dune-mmdg
 Version: 0.1
 Maintainer: maximilian.hoerl@mathematik.uni-stuttgart.de
 #depending on
-Depends: dune-common dune-geometry dune-mmesh
+Depends: dune-common dune-geometry dune-mmesh dune-istl
diff --git a/dune/mmdg/dg.hh b/dune/mmdg/dg.hh
index 67227159f95b204edecff0331c6507ee45f3715f..d115dfa2a5af452db9cdd78380620c9589efa1a9 100644
--- a/dune/mmdg/dg.hh
+++ b/dune/mmdg/dg.hh
@@ -10,6 +10,10 @@
 
 #include <dune/geometry/quadraturerules.hh>
 
+#include <dune/istl/bcrsmatrix.hh>
+#include <dune/istl/solver.hh>
+#include <dune/istl/umfpack.hh>
+
 #include <dune/mmdg/nonconformingp1vtkfunction.hh>
 
 template<class GridView, class Mapper, class Problem>
@@ -18,8 +22,8 @@ class DG
 public:
   using Scalar = typename GridView::ctype;
   static constexpr int dim = GridView::dimension;
-  using Matrix = Dune::DynamicMatrix<Scalar>; //NOTE: what is an appropriate sparse matrix type? -> BCRS
-  using Vector = Dune::DynamicVector<Scalar>;
+  using Matrix = Dune::BCRSMatrix<Dune::FieldMatrix<Scalar,1,1>>;
+  using Vector = Dune::BlockVector<Dune::FieldVector<Scalar,1>>;
 
   //constructor
   DG (const GridView& gridView, const Mapper& mapper,
@@ -27,9 +31,10 @@ public:
     gridView_(gridView), mapper_(mapper), problem_(problem),
     dof((1 + dim) * gridView.size(0))
     {
-      A = Matrix(dof, dof, 0.0); //initialize stiffness matrix
-      b = Vector(dof, 0.0); //initialize load vector
-      d = Vector(dof, 0.0); //initialize solution vector
+      //initialize stiffness matrix A, load vector b and solution vector d
+      A = Matrix(dof, dof, 4, 0.1, Matrix::implicit);
+      b = Vector(dof);
+      d = Vector(dof);
     }
 
   const void operator() (const Scalar K, const Scalar mu)
@@ -37,8 +42,9 @@ public:
     //assemble stiffness matrix A and load vector b
     assembleSLE(K, mu);
 
-    //NOTE: what would be an appropiate solver here?
-    A.solve(d, b);
+    Dune::InverseOperatorResult result;
+    Dune::UMFPack<Matrix> solver(A);
+    solver.apply(d, b, result);
 
     //storage for pressure data, for each element we store the
     //pressure at the corners of the element, the VTKFunction will
@@ -150,7 +156,7 @@ private:
       {
         //exact evaluation of
         // int_elem K*grad(phi_elem,i)*grad(phi_elem,i) dV
-        A[elemIdxSLE + i + 1][elemIdxSLE + i + 1] += K * elemVol;
+        A.entry(elemIdxSLE + i + 1, elemIdxSLE + i + 1) += K * elemVol;
       }
 
       //iterate over all intersection with the boundary of elem
@@ -206,7 +212,7 @@ private:
 
         //exact evaluation of
         // int_intersct mu*jump(phi_elem,0)*jump(phi_elem,0) ds
-        A[elemIdxSLE][elemIdxSLE] += mu * intersctVol;
+        A.entry(elemIdxSLE, elemIdxSLE) += mu * intersctVol;
 
         if (intersct.neighbor()) //intersct has neighboring element
         {
@@ -221,7 +227,7 @@ private:
             //and
             // int_intersct avg(K*grad(phi_elem,i))*jump(phi_elem,0) ds
             // = 0.5 * K * normal[i] * vol(intersct)
-            A[elemIdxSLE + i + 1][elemIdxSLE] +=
+            A.entry(elemIdxSLE + i + 1, elemIdxSLE) +=
               mu * linearIntegrals[i] - 0.5 * K * normal[i] * intersctVol;
 
             for (int j = 0; j <= i; j++)
@@ -232,7 +238,7 @@ private:
               //and
               // int_intersct avg(K*grad(phi_elem,i))*jump(phi_elem,j) ds
               // = 0.5 * K * normal[i] * int_intersct x_j ds
-              A[elemIdxSLE + i + 1][elemIdxSLE + j + 1]
+              A.entry(elemIdxSLE + i + 1, elemIdxSLE + j + 1)
                 += mu * quadraticIntregrals[i][j]
                   - 0.5 * K * (normal[i] * linearIntegrals[j]
                     + normal[j] * linearIntegrals[i]);
@@ -246,10 +252,11 @@ private:
 
           //exact evaluation of
           // int_intersct mu*jump(phi_elem,0)*jump(phi_neighbor,0) ds
-          A[elemIdxSLE][neighborIdxSLE] += -mu * intersctVol;
+          A.entry(elemIdxSLE, neighborIdxSLE) += -mu * intersctVol;
 
           //stiffness matrix A is symmetric
-          A[neighborIdxSLE][elemIdxSLE] += A[elemIdxSLE][neighborIdxSLE];
+          A.entry(neighborIdxSLE, elemIdxSLE) +=
+            A.entry(elemIdxSLE, neighborIdxSLE);
 
           for (int i = 0; i < dim; i++)
           {
@@ -261,7 +268,7 @@ private:
             // int_intersct avg(K*grad(phi_neighbor,i))
             //  *jump(phi_elem,0) ds
             // = 0.5 * K * normal[i] * vol(intersct)
-            A[elemIdxSLE + i + 1][neighborIdxSLE] +=
+            A.entry(elemIdxSLE + i + 1, neighborIdxSLE) +=
               -mu * linearIntegrals[i] + 0.5 * K * normal[i] * intersctVol;
 
             //we use the relations
@@ -272,14 +279,14 @@ private:
             // int_intersct avg(K*grad(phi_neighbor,i))
             //  *jump(phi_elem,0) ds
             // = 0.5 * K * normal[i] * vol(intersct)
-            A[elemIdxSLE][neighborIdxSLE + i + 1] +=
+            A.entry(elemIdxSLE, neighborIdxSLE + i + 1) +=
               -mu * linearIntegrals[i] - 0.5 * K * normal[i] * intersctVol;
 
             //stiffness matrix A is symmetric
-            A[neighborIdxSLE][elemIdxSLE + i + 1] +=
-              A[elemIdxSLE + i + 1][neighborIdxSLE];
-            A[neighborIdxSLE + i + 1][elemIdxSLE] +=
-              A[elemIdxSLE][neighborIdxSLE + i + 1];
+            A.entry(neighborIdxSLE, elemIdxSLE + i + 1) +=
+              A.entry(elemIdxSLE + i + 1, neighborIdxSLE);
+            A.entry(neighborIdxSLE + i + 1, elemIdxSLE) +=
+              A.entry(elemIdxSLE, neighborIdxSLE + i + 1);
 
             for (int j = 0; j <= i; j++)
             {
@@ -295,14 +302,14 @@ private:
               // int_intersct avg(K*grad(phi_elem,i))
               //  *jump(phi_neighbor,j) ds
               // = -0.5 * K * normal[i] * int_intersct x_j ds
-              A[elemIdxSLE + i + 1][neighborIdxSLE + j + 1] +=
+              A.entry(elemIdxSLE + i + 1, neighborIdxSLE + j + 1) +=
                 -mu * quadraticIntregrals[i][j]
                 - 0.5 * K * (normal[j] * linearIntegrals[i]
                   - normal[i] * linearIntegrals[j]);
 
               //stiffness matrix A is symmetric
-              A[neighborIdxSLE + j + 1][elemIdxSLE + i + 1] +=
-                A[elemIdxSLE + i + 1][neighborIdxSLE + j + 1];
+              A.entry(neighborIdxSLE + j + 1, elemIdxSLE + i + 1) +=
+                A.entry(elemIdxSLE + i + 1, neighborIdxSLE + j + 1);
 
               if (i != j)
               {
@@ -317,14 +324,14 @@ private:
                 // int_intersct avg(K*grad(phi_elem,j))
                 //  *jump(phi_neighbor,i) ds
                 // = -0.5 * K * normal[j] * int_intersct x_i ds
-                A[elemIdxSLE + j + 1][neighborIdxSLE + i + 1] +=
+                A.entry(elemIdxSLE + j + 1, neighborIdxSLE + i + 1) +=
                   -mu * quadraticIntregrals[i][j]
                   - 0.5 * K * (normal[i] * linearIntegrals[j]
                     - normal[j] * linearIntegrals[i]);
 
                 //stiffness matrix A is symmetric
-                A[neighborIdxSLE + i + 1][elemIdxSLE + j + 1] +=
-                  A[elemIdxSLE + j + 1][neighborIdxSLE + i + 1];
+                A.entry(neighborIdxSLE + i + 1, elemIdxSLE + j + 1) +=
+                  A.entry(elemIdxSLE + j + 1, neighborIdxSLE + i + 1);
               }
             }
           }
@@ -339,7 +346,7 @@ private:
             // int_intersct avg(K*grad(phi_elem,i))
             //  *jump(phi_elem,0) ds
             // = K * normal[i] * vol(intersct)
-            A[elemIdxSLE + i + 1][elemIdxSLE] +=
+            A.entry(elemIdxSLE + i + 1, elemIdxSLE) +=
               mu * linearIntegrals[i] - 0.5 * K * normal[i] * intersctVol;
 
             for (int j = 0; j <= i; j++)
@@ -351,7 +358,7 @@ private:
               // int_intersct avg(K*grad(phi_elem,i))
               //  *jump(phi_elem,j) ds
               // = 0.5 * K * normal[i] * int_intersct x_j ds
-              A[elemIdxSLE + i + 1][elemIdxSLE + j + 1] +=
+              A.entry(elemIdxSLE + i + 1, elemIdxSLE + j + 1) +=
                 mu * quadraticIntregrals[i][j]
                 - 0.5 * K * (normal[i] * linearIntegrals[j]
                   + normal[j] * linearIntegrals[i]);
@@ -363,22 +370,25 @@ private:
       //stiffness matrix A is symmetric
       for (int i = 0; i < dim; i++)
       {
-        A[elemIdxSLE][elemIdxSLE + i + 1] = A[elemIdxSLE + i + 1][elemIdxSLE];
+        A.entry(elemIdxSLE, elemIdxSLE + i + 1) =
+          A.entry(elemIdxSLE + i + 1, elemIdxSLE);
 
         for(int j = 0; j < i; j++)
         {
-          A[elemIdxSLE + j + 1][elemIdxSLE + i + 1] =
-            A[elemIdxSLE + i + 1][elemIdxSLE + j + 1];
+          A.entry(elemIdxSLE + j + 1, elemIdxSLE + i + 1) =
+            A.entry(elemIdxSLE + i + 1, elemIdxSLE + j + 1);
         }
       }
     }
 
     //NOTE: check if A is symmetric
-    for (int i = 0; i < dof; i++)
-      for (int j = 0; j < i; j++)
-        /*assert*/if(std::abs(A[i][j] - A[j][i]) >
+  /*  for (int i = 0; i < dof; i++)
+      for (int j = 0; j < i; j++) */
+        /*assert*//*if(std::abs(A[i][j] - A[j][i]) >
           std::numeric_limits<Scalar>::epsilon())
-            std::cout << i << ", " << j << std::endl;
+            std::cout << i << ", " << j << std::endl; */
+
+    A.compress();
   }