Tsu attended high school in Forest Hills, Queens, N.Y. At Princeton he majored in physics, won the Class of 1861 Prize in mathematics, and junior year was elected a Phi Beta Kappa. His hobbies were bridge and chess. He belonged to Dial Lodge.
Tsu earned a Ph.D. in particle physics at Columbia University and taught at Rutgers and the University of Pittsburgh.
In 1975 he changed careers, joining Bank of America in San Francisco first as a long-term economic forecaster and then as a senior risk analyst. He retired in 2000. He traveled the world with his wife, Winifred, and indulged in his lifelong passion, Chinese history of the Ming and early Qing dynasties, the latter the final imperial dynasty lasting until 1912.
Tsu is survived by Winifred, son Kenneth, brother Kung ’61, and many nephews, nieces, grandnephews, and grandnieces.