1. Depto. Ecuaciones Diferenciales y Análisis Numérico, Facultad de Matemáticas, Universidad de Sevilla, Sevilla, Spain
2. Laboratory of Mathematics Modeling and Applications, University of Adrar, University of Adrar, Adrar, Algeria
3. Department of Mathematics, University of Science and Technology Mohamed-Boudiaf El Mnaouar, Oran, Oran, Algeria