His large staff uses computers to help him analyze his models. Calatrava guesses that even Antonio Gaudi -- Spain's singular surrealist Catalan architect who at the turn of the last century was testing structural models with strings and weights -- would use computers if he were designing today. But a couple of factors distinguish Calatrava from the current crop of star architects. First, he has a second profession. He is an engineer. Most architects are not engineers, and most engineers do not design buildings. They graduate from different schools, and though they must collaborate on the same projects, they eye each other with the mutually dependent suspicions of the sausagemaker and the health inspector.