We avoid as as much as possible the order reduction of Rosenbrock methods when they
are applied to nonlinear partial differential equations by means of a similar technique to the one
used previously by us for the linear case. For this we use a suitable choice of boundary values for the
internal stages. The main difference from the linear case comes from the difficulty to calculate those
boundary values exactly in terms of data. In any case, the implementation is cheap and simple since,
at each stage, just some additional terms concerning those boundary values and not the whole grid
must be added to what would be the standard method of lines.
