[1] Loyola Coll, Dept Math, Chennai 600034, India
[2] De La Salle Univ, Coll Sci, Dept Math & Stat, 2401 Taft Ave, Manila 1004, Metro Manila, Philippines
[3] Vellore Inst Technol, Sch Adv Sci, Chennai 600127, India
[4] Khawaja Fareed Univ Engn & Informat Technol, Inst Math, Abu Dhabi Rd, Rahim Yar Khan 64200, Pakistan
[5] King Saudi Univ, Math Dept, Riyadh 145111, Saudi Arabia
[6] Wroclaw Univ Sci & Technol, Fac Mech Engn, Wroclaw, Poland