1. School of Mathematics and Statistics and Hubei Key Laboratory of Engineering Modeling and Scientific Computing, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China.
2. Departamento de Matemática, Universidade Federal de São Carlos, 13565–905, São Carlos SP, Brazil.
3. Departamento de Ecuaciones Diferenciales Y Análisis Numérico, Universidad de Sevilla, 41080 Seville, Spain.