To Rafael Guarga, Ismael, Hugo and Susana
the team with which I started.
To Carlos López for his support.
To Isaac Bromberg for his help.
To my colleagues at the CeCal.
To my former colleagues of the IMFIA.
To Nicolas Silveira, a great helper in this project.
To Alejandro Borche, who introduced me in the
``shallow waters''
and to the CFD as well