Sax Elliot, 84, former basketball coach at Beverly Hills High School and Cal State L.A. Elliot, who coached at Beverly Hills from 1935 to 1950, was responsible for the school's unique "Swim-Gym"--a retractable gymnasium floor above a swimming pool. The Swim-Gym was featured in Frank Capra's 1946 classic "It's a Wonderful Life" in a scene where a miffed suitor opens it and dancing couples fall into the pool. The Swim-Gym was the first facility to use glass basketball backboards, now the standard for collegiate and professional games. Elliot left Beverly Hills High to become head basketball coach at Los Angeles State College, now Cal State L.A. He is credited with inventing the square on the glass backboard to improve shooting and the multicolored basketball adopted by the former American Basketball Assn. When he left Cal State L.A. in 1962, he was succeeded by future Los Angeles Laker Coach Bill Sharman. On Nov. 19 in Montecito.