1. Faculty of Pure and Applied Mathematics, Hugo Steinhaus Center, Wroclaw University of Science and Technology Wybrzeze Wyspianskiego, 27 , 50-370 Wroclaw, Poland.
2. Research and Development Centre, KGHM Cuprum Ltd , Wroclaw, Poland.
3. Faculty of Geoengineering, Mining and Geology, Wroclaw University of Science and Technology , Wroclaw, Poland.