/// <summary>
        /// instantiation of <see cref="ApplicationWithSolver{T}.Timestepping"/>
        /// </summary>
        protected override void InitSolver()
        {
            if (base.Timestepping != null)
            {
                return;
            }

            XdgTimestepping solver = new XdgTimestepping(
                XOperator,
                CurrentState.Fields,
                CurrentResidual.Fields,
                Control.TimeSteppingScheme,
                UpdateLevelset,
                LevelSetHandling,
                MultigridOperatorConfig,
                MultigridSequence,
                Control.AgglomerationThreshold,
                Control.LinearSolver, Control.NonLinearSolver);

            base.Timestepping = solver;

            if (!object.ReferenceEquals(base.LsTrk, solver.LsTrk))
            {
                throw new ApplicationException();
            }
        }
        /// <summary>
        ///
        /// </summary>
        protected override void InitSolver()
        {
            if (base.Timestepping != null)
            {
                return;
            }

            XdgTimestepping solver = new XdgTimestepping(
                SOperator,
                CurrentState.Fields,
                CurrentResidual.Fields,
                Control.TimeSteppingScheme,
                MultigridOperatorConfig,
                MultigridSequence,
                Control.LinearSolver, Control.NonLinearSolver);

            LsTrk = solver.LsTrk; // register the dummy tracker which the solver created internally for the DG case

            base.Timestepping = solver;
        }