Real Zeros of Polynomials

Abstract

Let A be a polynomial over Z, Q or Q(IX) where IX is a real algebraic number. The problem is to compute a sequence of disjoint intervals with rational endpoints, each containing exactly one real zero of A and together containing all real zeros of A. We describe an algorithm due to Kronecker based on the minimum root separation, Sturm's algorithm, an algorithm based on Rolle's theorem due to Collins and Loos and the modified Uspensky algorithm due to Collins and Aritas. For the last algorithm a recursive version with correctness proof is given which appears in print for the first time.