Discrete systems, efficiency and bug fixing Added: - Implemented Runge-Kutta solver of order 4. - Discrete linear system time evolution. - Discretization of continuous linear system. - Allow to pass closures as input for the time evolution of a system. - Example for system discretization. Changed: - Improve efficiency using LU decomposition to solve implicit system. Fixed: - Corrected the transformation from transfer function to state-space form.