[1] Univ Haripur, Dept Pure & Appl Math, Haripur, KP, Pakistan
[2] Mehran Univ Engn Technol, Dept BSRS, Jamshoro, Pakistan
[3] Penn State Univ, Dept Math, York Campus,1031 Edgecomb Ave, York, PA 17403 USA
[4] Abdul Wali Khan Univ, Dept Math, Garden Campus Mardan, Mardan, KP, Pakistan
[5] Taif Univ, Dept Math, Coll Sci, POB 11099, At Taif 21944, Saudi Arabia
[6] Univ Engn & Technol, Dept Basic Sci & Islamiyat, Peshawar, Pakistan
[7] Quaid e Awam Univ Engn Sci & Technol, Dept Math & Stat, Nawabshah, Sindh, Pakistan