  An algorithm for computing the limit of a quotient of bivariate real analytic
functions has been developed by one of the authors in (Limits of quotients of
bivariate real analytic functions, Journal of Symbolic Computation, 50, 2013,
197 207). In this paper we provide a theoretical method based on the work
developed in that article to determine the existence of the limit of a quotient
of two polynomial functions of three variables. An algorithm to compute such
limits, in the case where the polynomials have rational coefficients, or more
generally, coefficients in a real finite extension of the rationals, is also
described.
