[Maxima] plotting results of rk

[Martin Schönecker]

> This returns me a list of [t,x,y]. How can I plot x(t) and y(t)?

Separate your values into pairs [t,x] and [t,y] and use the discrete 
option of plot2d:

xtvalues: map(lambda([e], part(e,[1,2])), res);

ytvalues: map(lambda([e], part(e,[1,3])), res);

plot2d([
     [discrete, xtvalues],
     [discrete, ytvalues]
]);