Properly setup the shared_ptr member

dune/solvers/iterationsteps/projectedgradientstep.hh

@@ -34,8 +34,10 @@ public:
 
     //! Constructor that gets the quadratic energy functional x^T mat x - rhs^T*x, and the initial iterate
     ProjectedGradientStep(const MatrixType& mat, VectorType& x, const VectorType& rhs)
-        : Base(x), mat_(mat), rhs_(rhs)
-    {}
+        : Base(x), rhs_(&rhs)
+    {
+        mat_     = Dune::stackobject_to_shared_ptr(mat);
+    }
 
     /** \brief Compute the generalized Cauchy point along a given direction. This is sometimes needed in
      *         nonlinear programming where this direction then corresponds to the gradient of the nonlinear function