1. Department of Mathematics, Quaid-I-Azam University, Islamabad, Pakistan + Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
2. Department of Mathematics, Quaid-I-Azam University, Islamabad, Pakistan
3. Research Centre for Modeling and Simulation (RCMS), National University of Sciences and Technology (NUST), Sector H, Islamabad, Pakistan
4. Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia