I have worked in different subfields of Applied Mathematics. Probably my most successful reseach has been that on the numerical integration of Hamiltonian problems. It got me an invitation to speak at the 1994 International Congress of Mathematicians (Zurich) (I think this was the first time a Spaniard was ever invited) and also the Dahlquist prize of SIAM in 1995 (the first time it was awarded). This sort of research has given rise to a very active area, nowadays referred to as Geometric Integration (by the way, a term I coined). I have also received the Iberdrola research prize (awarded once a year by a committee of Nobel prize winners to the best researcher in Spain across all fields), the prize of the Spanish Academy of Sciences, etc. (see Prizes in the menu bar). I also happen to be one of the most widely cited Spanish scientist, in spite of the fact that I had to interrup my research to serve as a Rector.