diff --git a/src/quaternion.hh b/src/quaternion.hh
index 722d96ee1eac054e1784288aaf0c04d36d750ab5..89af3afc24bf82f22e812286c7d30457a9a3e5f0 100644
--- a/src/quaternion.hh
+++ b/src/quaternion.hh
@@ -139,6 +139,24 @@ public:
         return d;
     }
             
+    void getFirstDerivativesOfDirectors(Dune::array<Dune::FieldMatrix<double,3 , 4>, 3>& dd_dq) const
+    {
+        const Quaternion<T>& q = (*this);
+
+        dd_dq[0][0][0] =  2*q[0];  dd_dq[0][0][1] = -2*q[1];  dd_dq[0][0][2] = -2*q[2];  dd_dq[0][0][3] =  2*q[3];
+        dd_dq[0][1][0] =  2*q[1];  dd_dq[0][1][1] =  2*q[0];  dd_dq[0][1][2] =  2*q[3];  dd_dq[0][1][3] =  2*q[2];
+        dd_dq[0][2][0] =  2*q[2];  dd_dq[0][2][1] = -2*q[3];  dd_dq[0][2][2] =  2*q[0];  dd_dq[0][2][3] = -2*q[1];
+
+        dd_dq[1][0][0] =  2*q[1];  dd_dq[1][0][1] =  2*q[0];  dd_dq[1][0][2] = -2*q[3];  dd_dq[1][0][3] = -2*q[2];
+        dd_dq[1][1][0] = -2*q[0];  dd_dq[1][1][1] =  2*q[1];  dd_dq[1][1][2] = -2*q[2];  dd_dq[1][1][3] =  2*q[3];
+        dd_dq[1][2][0] =  2*q[3];  dd_dq[1][2][1] =  2*q[2];  dd_dq[1][2][2] =  2*q[1];  dd_dq[1][2][3] =  2*q[0];
+
+        dd_dq[2][0][0] =  2*q[2];  dd_dq[2][0][1] =  2*q[3];  dd_dq[2][0][2] =  2*q[0];  dd_dq[2][0][3] =  2*q[1];
+        dd_dq[2][1][0] = -2*q[3];  dd_dq[2][1][1] =  2*q[2];  dd_dq[2][1][2] =  2*q[1];  dd_dq[2][1][3] = -2*q[0];
+        dd_dq[2][2][0] = -2*q[0];  dd_dq[2][2][1] = -2*q[1];  dd_dq[2][2][2] =  2*q[2];  dd_dq[2][2][3] =  2*q[3];
+
+    }
+
     void getFirstDerivativesOfDirectors(Dune::array<Dune::array<Dune::FieldVector<double,3>, 3>, 3>& dd_dvj) const
     {
         const Quaternion<T>& q = (*this);