Introduction

The purpose of this chapter is to present some tools enabling to analyze system of equations i.e. to get some a-priori information on the roots without solving the systems. These tools allows one to determine that there is a unique solution in a given box and provides a mean to calculate it in a safe way. Hence they are essential to provide a guaranteed solution for a system of equations.

Note that a generic analyzer based on the ALIAS parser has been developed and will be presented in the chapter devoted to the parser. This generic analyzer enable to analyze almost any type of system in which at least one equation is algebraic in at least one of the unknowns.