Legendre, Adrien-Marie (1752-1833)

French mathematician who was particularly interested in number theory, celestial mechanics, and elliptic functions. Legendre was born in Paris and studied there at the Collège Mazarin. During the French Revolution, he became head of the government department established to standardize French weights and measures 1794, as well as professor at the Institut de Marat. From 1813 he was chief of the Bureau de Longitudes. In 1783-84 he introduced to celestial mechanics what are now known as Legendre polynomials. These are solutions to a second-order differential equation. In number theory his most significant result was the law of reciprocity of quadratic residues (established more firmly by German mathematician Karl Gauss 1801) and the law of the distribution of prime numbers 1798. In his school textbook Eléments de géometrie 1794, Legendre gave the single proof of the irrationality of and the first proof of the irrationality of 2. He published a textbook and tables on elliptical functions 1825-26.