  A new standpoint on financial time series, without the use of any
mathematical model and of probabilistic tools, yields not only a rigorous
approach of trends and volatility, but also efficient calculations which were
already successfully applied in automatic control and in signal processing. It
is based on a theorem due to P. Cartier and Y. Perrin, which was published in
1995. The above results are employed for sketching a dynamical portfolio and
strategy management, without any global optimization technique. Numerous
computer simulations are presented.
