1. Laboratory of RIIMA, Faculty of Mathematics, USTHB, PB 32 El Alia 16111 Algiers, Algeria
2. Centre Universitaire Morsli Abdellah de Tipaza, Tipaza, Algeria
3. Laboratory of Applied Mathematics, Faculty of Exact Sciences, Bejaia University, Bejaia, Algeria
4. Laboratory LE2I UMR CNRS 6306, University of Bourgogne, Dijon, France