1. Department of Mathematics, AM2CSI Group, MSISI Laboratory, FST Errachidia , Moulay Ismaïl University of Meknes, Meknes, Errachidia 52202 , Morocco
2. Lab-SIV, Ibnou Zohr University , Agadir 80000 , Morocco
3. Cadi Ayyad University, Faculty of Sciences Semlalia, LMDP, UMMISCO (IRD-UPMC) , B.P. 2390, Marrakesh , Morocco