1. Laboratory of Applied Mathematics & Scientific Computing LMACS, Faculty of Sciences and Technics, Sultan Moulay Slimane University, P.O. Box 523, Beni Mellal 23000, Morocco
2. Department of Mathematics, Faculty of Organizational Sciences, University of Belgrade, Jove Ilića 154, 11000 Belgrade, Serbia
3. Department of Mathematics and Informatics, Faculty of Science, University of Kragujevac, 34000 Kragujevac, Serbia
4. Faculty of Mechanical Engineering, University of Belgrade, 11000 Belgrade, Serbia