1. Weierstrass Institute for Applied Analysis and Stochastics , Leibniz Institute in Forschungsverbund Berlin e.V. (WIAS), Mohrenstr. 39, 10117; and Department of Mathematics and Computer Science, Freie Universität of Berlin, Arnimallee 6, 14195 Berlin , Germany
2. Department of Numerical Mathematics , Faculty of Mathematics and Physics , Charles University , Sokolovská 83, 18675 Praha 8 , Czech Republic
3. Weierstrass Institute for Applied Analysis and Stochastics , Leibniz Institute in Forschungsverbund Berlin e. V. (WIAS), Mohrenstr. 39, 10117 Berlin , Germany