In this talk, we will review recent progress in practical calculations of Lyapunov exponents. The exponents provide a fundamental characteristic of dynamical systems describing systems stability, the dimension of the attractor, and other properties. The sum of Lyapunov exponents provides the rate of Gibbs entropy generation in a non-equilibrium steady state and is given by a Green-Kubo type formula. We illustrate this by calculating the sum in the short correlation time limit. We introduce general representations of the Lyapunov exponents in terms of the flow and stress the simplification in practically relevant three-dimensional case. Calculations in short correlation time limit are considered.