Remove superfluous operator()

src/compute_state.cc

@@ -15,8 +15,6 @@ class DecayingExponential {
   typedef Dune::FieldVector<double, 1> VectorType;
   typedef Dune::FieldMatrix<double, 1, 1> MatrixType;
 
-  double operator()(VectorType const &u) const { return std::exp(-u[0]); }
-
   void directionalSubDiff(VectorType const &u, VectorType const &v,
                           Interval<double> &D) const {
     D[0] = D[1] = v[0] * (-std::exp(-u[0]));