born Aug. 21, 1789, Paris, France
died May 23, 1857, Sceaux
French mathematician, pioneer of analysis and group theory .
After a career as a military engineer in Napoleon's navy, he wrote a treatise in 1813 that became the basis of the theory of complex variable s. He also clarified the theory of calculus by developing the concepts of limit s and continuity , laid the foundations for the mathematical theory of elasticity, and made important contributions to number theory . He is considered one of the greatest mathematicians of the modern era.