About the Authors

Wenli Cai

Affiliation Department of Mathematical Sciences, Tsinghua University, Beijing, China

Ning Su

Affiliation Department of Mathematical Sciences, Tsinghua University, Beijing, China

Xiangdong Liu

xdliu@ustb.edu.cn

Affiliation Department of Financial Engineering, Donlinks School of Economics and Management, University of Science and Technology Beijing, Beijing, China

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: WLC NS XDL. Performed the experiments: WLC. Analyzed the data: WLC NS XDL. Contributed to the writing of the manuscript: WLC NS XDL.