Joseph-Louis Lagrange
1736–1813, Turin, Kingdom of Sardinia (now Italy), Paris, France
Italian-born French-Prussian mathematician who transformed mechanics into a branch of mathematical analysis and made foundational contributions to the calculus of variations, number theory and the theory of equations.
Lagrange was born in Turin, then the capital of the Kingdom of Sardinia, and was largely self-taught in mathematics. At just 19 he was appointed professor of mathematics at the Royal Artillery School in Turin, and his early correspondence with Euler on the calculus of variations and the tautochrone quickly established his reputation. In 1766 he succeeded Euler as director of mathematics at the Prussian Academy of Sciences in Berlin, where he spent twenty highly productive years.
In 1787 Lagrange moved to Paris to join the Académie des Sciences, and he survived the French Revolution, becoming the first professor of analysis at the newly founded École Polytechnique in 1794 and helping to design the metric system. His treatise Mécanique analytique (1788) recast all of mechanics in terms of differential equations without a single diagram. He also proved that every positive integer is a sum of four squares (1770) and Wilson's theorem (1771), and his 1770 study of permutations of the roots of equations anticipated group theory. He died in Paris in 1813.
Workplaces: Royal Artillery School, Turin, Prussian Academy of Sciences, Berlin, École Polytechnique, Paris
Italy, Germany, France