[1] King Faisal Univ, Dept Basic Sci, Preparatory Year, Al Hasa 31982, Saudi Arabia
[2] King Faisal Univ, Coll Sci, Dept Math, Al Hasa 31982, Saudi Arabia
[3] Micheal Okpara Univ Agr, Dept Math, Umudike, Umuahia Abia St, Nigeria
[4] Univ Management & Technol, Dept Math, Lahore 54770, Pakistan
[5] Sefako Makgatho Hlth Sci Univ, Dept Math & Appl Math, ZA-0204 Pretoria, South Africa