The purpose of this paper is to point out an ambiguity in a formula connecting the logarithmic part of the integral of a rational function and certain subresultants. The implementation of this formula in AXIOM can lead to incorrect results.

The author gives an example showing that one can get incorrect answers when using AXIOM 2.0. He suggests four different methods by which to overcome the difficulty. The user can choose a method depending on the computations that need to be done.