Diana Dolicanin1 and Valery G. Romanovski2
1Faculty of Electronic Engineering,
Department of Mathematics
P.O. Box 73 18000 Nis, Serbia and Montenegro
(e-mail:
dolicanin_d@yahoo.com)
2Center for Applied Mathematics and Theoretical Physics,
University of Maribor,
Krekova 2, SI-2000 Maribor, Slovenia
(e-mail: valery.romanovsky@uni-mb.si)