1. HUN-REN Institute for Computer Science and Control, Systems and Control Laboratory, Budapest, Hungary; Eötvös Lóránd University, Faculty of Informatics, Department of Numerical Analysis, Budapest, Hungary.
2. Eötvös Lóránd University, Faculty of Informatics, Department of Numerical Analysis, Budapest, Hungary.
3. HUN-REN Institute for Computer Science and Control, Systems and Control Laboratory, Budapest, Hungary.