Abstract :
Since high school, I wanted to do a Ph.D. in physics. After graduating from the ETH Zurich with degrees in electrical engineering and mathematics, I was appointed as an assistant and doctoral student in solid-state physics at the ETH. A few months later, I heard that someone named Kalman was coming to the ETH from the United States. The name rang a bell, as I had encountered the Kalman filter in my undergraduate years. Shortly thereafter I decided to take on the challenge and do my Ph.D. under Rudy´s supervision. Rudy consulted with Eduard Stiefel, one of my former teachers and a respected professor of applied mathematics at the ETH, and he offered me a position provided that I already had a publication. That happened to be the case (my Diplomarbeit-diploma thesis-in mathematics was published in 1976). Thus started my journey in systems and control, a field about which I knew very little at the time. In the years that followed there were ups and downs; about eight months before graduating I considered abandoning the effort. Then things started falling into place. Important for this development were my encounters with Jan Willems and Paul Fuhrmann.
