Model of time-varying linear systems and Kolmogorov equations

In the paper an approximate model of time-varying linear systems using a sequence of timeinvariant systems is suggested. The conditions for validity of the approximation are proven with a theorem. Examples comparing the numerical solution of the original system and the analytical solution of the model are given. For the system under the consideration a new criterion giving sufficient conditions for robust Lagrange stability is suggested. The criterion is proven with a theorem. Examples are given showing stable and non stable solutions of a time-varying system and the results are compared with the numerical Runge-Kutta solution of the system. In the paper an important application of the described method of solution of linear systems with timevarying coefficients, namely analytical solution of the Kolmogorov equations is shown.