[1] Chengdu Univ, Sch Informat Sci & Engn, Chengdu, Peoples R China
[2] Univ Lahore, Dept Math, Pakpattan Campus, Pakpattan 57400, Pakistan
[3] Inst Southern Punjab, Dept Math & Stat, Multan, Pakistan
[4] COMSATS Univ Islamabad, Dept Math, Lahore Campus, Lahore, Pakistan