Joseph-Louis Lagrange was a French mathematician and mathematical physicist who developed the calculus of variations. He is regarded as the greatest mathematician of the eighteenth century. His work Mècanique Analytique (Analytical Mechanics), published in 1788, is considered a mathematical masterpiece that covered nearly every area of pure mathematics without the use of a single diagram. This treatise offered the most comprehensive treatment of classical mechanics since Newton and formed a basis for the development of mathematical physics in the nineteenth century.

Lagrange also established the theory of differential equations, invented the method of solving differential equations known as variation of parameters, and provided many new solutions and theorems in number theory. Between 1772 and 1788, Lagrange re-formulated Classical/Newtonian mechanics to simplify formulas and ease calculations. These mechanics are called Lagrangian mechanics.

He succeeded Leonhard Euler as the director of the prestigious Berlin Academy in 1766 on the recommendation of Euler and Jean Le Rond D’Alembert. Jean Baptiste Joseph Fourier, who is credited with the discovery of the greenhouse effect, and Simeon Poisson, an important French mathematician and physicist, were doctoral students of Lagrange.

Lagrange is one of the 72 prominent French scientists who were commemorated on plaques at the first stage of the Eiffel Tower when it first opened. The lunar crater Lagrange also bears his name.

Sources

• Cleveland, Cutler (Lead Author); Peter Saundry (Topic Editor). 2007. "Lagrange, Joseph-Louis." In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth September 15, 2006; Last revised April 18, 2007; Retrieved February 17, 2009]. 
• Wikipedia Contributors, Joseph Louis Lagrange, Wikipedia The Free Encyclopedia, Accessed 17 February 2009.