Beste Remco,
My question is, what are your thoughts on how to implement integration in a nice fashion? I tought about implementing some kind of antiderivative operator wich can be used in expressions and gives the indefinite integral. The reason I preffer operators to member function is that it allows unsolvable integrals to remain in the equation and still be numerically evaluable. In this fashion I would like to create a differential operator so ODE's and PDE's can be expressed in Ginac and numerically solved.
There is already a class "integral" in GiNaC, as you may know. This class contains a left and a right boundary, so it is not immediately suitable for representing an indefinite integral, but I think it could be made suitable. Instead of holding a left and a right boundary, it could hold a more general "integration_region" object that should be in a certain state in the case of an indefinite integral or in another state representing an interval. The advantage is that this way it is not necessary to introduce a new class for a different kind of integral. Veel succes! Chris