1. Department of Mathematics , AMNEA Group, MAIS Laboratory, Faculty of Sciences and Technics , Moulay Ismail B. P. 509 , Errachidia , Morocco .
2. Department of Mathematics, AMNEA Group , MAIS Laboratory, Faculty of Sciences and Technics , Moulay Ismail B. P. 509 , Errachidia , Morocco .
3. Department of Mathematics, Faculty of Sciences , Mohammed V University of Rabat , Morocco .
4. R&D Unit CIDMA, Department of Mathematics , University of Aveiro , Aveiro , Portugal .