ZHANG Zhen1,2, MA Siliang1, LIU Jianguo3, LIU Hui1
1. Institute of Mathematics, Jilin University, Changchun 130012, China;2. Estate Group, Daqing Oilfield, Daqing 163453, Heilongjiang Province, China;3. College of Informational Technology, Changchun Normal University, Changchun 130032, China