1. School of Mathematics and Computational Science, Xiangtan University, Xiangtan, 411105, Hunan, People’s Republic of China.
2. Hunan Key Laboratory for Computation and Simulation in Science and Engineering, Xiangtan University, Xiangtan, 411105, Hunan, People’s Republic of China.
3. Department of Mathematical Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4020 USA.