1. Department of Mathematics and Applied MathematicsUniversity of Pretoria Pretoria South Africa
2. Clermont Université, LIMOS, UMR 6158 CNRSUniversité Blaise Pascal Clermont‐Ferrand France
3. Department of Mathematics and Descriptive Geometry, Faculty of Mechanical Engineering and IT4Innovations National Supercomputing CenterVŠB—Technical University of Ostrava Ostrava Czech Republic