1. Institute of Applied Analysis and Numerical Simulation, Universität Stuttgart, 70569, Stuttgart, Germany.
2. Weierstrass Institute for Applied Analysis and Stochastics (WIAS), 10117 Berlin, Germany, and Department of Mathematics and Computer Science, Freie Universität Berlin, 14195 Berlin, Germany.
3. Department of Numerical Mathematics, Faculty of Mathematics and Physics, Charles University, Praha 8, 18675, Czech Republic.