This is an adapted Runge Kutta method (theoretical background e.g. in Hairer, Lubich, Roche "The numerical solution of differential-algebraic systems by runge-kutta methods") to solve DAEs. Already implemented is the Radau II A method of stage 1, 2 and 3 but basically every Butcher tableau can be implemented (see code for details). A simple example (the mathematical pendulum) is provided to show the usage. The nonlinear system solver is the newton method, but it can also be exchanged.
- added argument to give an estimated solution