1. University of Heidelberg; Institute of Applied Mathematics and IWR; Im Neuenheimer Feld 294 69120 Heidelberg Germany
2. Institute of Information Theory and Automation, of the CAS; Pod vodárenskou věží 4, CZ-182 08 Prague 8 Czech Republic
3. Faculty of Civil Engineering; Czech Technical University; Thákurova 7, 166 29 Prague Czech Republic