I.I. Vasilyeva - Assistant, Department of Mathematical Modeling and Computer Technologies, Yelets State University named after I.A. Bunin. E-mail: irinavsl@yandex.ru O.B. Gladkikh - Ph.D. (Phys.-Math.), Associate Professor, Department of Mathematical Modeling and Computer Technologies, Yelets State University named after I.A. Bunin. E-mail: og1972@rambler.ru