1. Institute of Mathematics, Eötvös Loránd University ; and Institute of Mathematics , Budapest University of Technology and Economics ; and MTA-ELTE NumNet Research Group, 1111 Budapest , Egry József u. 1 , Hungary
2. Institute of Mathematics, Eötvös Loránd University ; and Department of Differential Equations , Budapest University of Technology and Economics; and MTA-ELTE NumNet Research Group, 1111 Budapest , Egry József u. 1 , Hungary
3. Department of Analysis , Budapest University of Technology and Economics ; and MTA-ELTE NumNet Research Group, 1111 Budapest , Egry József u. 1 , Hungary
4. Faculty of Education , Faculty of Mathematics and Physics at University of Ljubljana ; and Institute of Mathematics, Physics and Mechanics, Jadranska ul. 19, 1000 Ljubljana , Slovenia