Mathematician, born in St Omer, N France. He studied at the Ecole Polytechnique and the Ecole des Ponts et Chaussées, where he trained as an engineer. He taught at the Ecole Polytechnique, the Collége de France, and the University of Paris. In 1836 he founded the Journal de Mathématiques, which he edited for nearly 40 years. His work in analysis continued the study of algebraic function theory begun by Niels Abel and Carl Jacobi, and he studied the theory of differential equations, mathematical physics, and celestial mechanics.