Analytic machines

In this paper we present some results about it analytic machines regarding th power of computations over sf bf Q and sf bf R, solutions of differential equations and the stability problem of dynamical systems. We first explain the machine model, wich is a kind of sc Blum-Shub-Smale machine enhanced by infinite convergent computiations. Next, we compare the computional power of such machinesofer the fields sf bf Q and sf bf R showing that finite computations with real numbers can be simulated by infinite converging computations on rational numbers, but the precision of the approximation is not known during the process. Our attention is then shifted to it ordinary differential equations (ODEs), dynamical systems described by ODEs and the undecidability of a class of stability problems for dynamical syste