1. Dipartimento di Matematica and AM, Alma Mater Studiorum - Università di Bologna, Piazza di Porta S. Donato, 5, I-40127 Bologna, Italy, IMATI-CNR, Pavia, and IAC-CNR, Bari, Italy.
2. High Performance Computing Center, Institute of Applied Physics and Computational Mathematics, Beijing, 100088, China.