[1] North Carolina State Univ, Dept Math, Raleigh, NC 27695 USA
[2] Southern Univ Sci & Technol, Dept Math, Shenzhen 518055, Peoples R China
[3] Rhein Westfal TH Aachen, Dept Math, D-52056 Aachen, Germany
[4] Southern Univ Sci & Technol, Dept Math, SUSTech Int Ctr Math, Shenzhen 518055, Peoples R China
[5] Southern Univ Sci & Technol, Guangdong Prov Key Lab Computat Sci & Mat Design, Shenzhen 518055, Peoples R China
[6] Johannes Gutenberg Univ Mainz, Inst Math, Mainz, Germany