1. Computational Center , Federal State Unitary Enterprise “Russian Federal Nuclear Center – Zababakhin All–Russia Research Institute of Technical Physics” , Snezhinsk , Chelyabinsk Region, 456770 , Russia
2. Department of Mathematics , Federal State Unitary Enterprise “Russian Federal Nuclear Center – Zababakhin All–Russia Research Institute of Technical Physics” , Snezhinsk , Chelyabinsk Region, 456770 , Russia