1. Supercomputer Technology Inst., Lobachevsky State University of Nizhny Novgorod , Nizhny Novgorod, Russia
2. Department of Applied Mathematics, National Chiao Tung University , Hsinchu, Taiwan
3. Inst. of Information Technology, Mathematics, and Mechanics, Lobachevsky State University of Nizhny Novgorod , Nizhny Novgorod, Russia