Joseph Pierre LaSalle (born 28 May 1916 in State College, Pennsylvania; died 7 July 1983 in Little Compton, Rhode Island) was an American mathematician specialising in dynamical systems and responsible for important contributions to stability theory, such as LaSalle's invariance principle which bears his name.
Joseph LaSalle defended his Ph.D. thesis on ″Pseudo-Normed Linear Sets over Valued Rings″ at the California Institute of Technology in 1941.
[4] In 1962-1963 he was President of the Society for Industrial and Applied Mathematics (SIAM)[6] and was a member of its board of trustees in 1964–1967.
[4] In 1964 he became the first director of the Center for Dynamical Systems at Brown University, where he was also the chairman of the Division of Applied Mathematics in 1968–1973.
[8] Together with J. K. Hale, LaSalle was the recipient of the 1965 Chauvenet Prize for their article, ″Differential Equations: Linearity vs. Nonlinearity″,[9] published in the SIAM Review.