Computing self-intersection curves of rational ruled surfaces

An algorithm is presented to compute the self-intersection curves of a rational ruled surface based on the theory of mu-bases. The algorithm starts by constructing the principal subresultants for a mu-basis of the rational ruled Surface. The principal subresultant coefficients provide information about not only the parametric loci of the self-intersection Curves, but also the orders of the self-intersection curves. Based oil this observation. all efficient algorithm is provided to compute the parametric loci of the self-intersection Curves as well as their corresponding orders. The isolated singular points of the rational ruled surface are also computed. (c) 2008 Elsevier B.V. All rights reserved.