French mathematician and physicist famous for his pioneer work on the representation of functions by trigonometric series, Fourier was born at Auxere on March 21, 1768, the son of a tailor. He became a teacher in mathematics in 1784 at the military school there. He taught at the Ecole Normale at Paris from its founding in 1795, where his success soon led to the offer of the Chair of Analysis at the Ecole Polytechnique. In 1807 he was made a member of the academy of sciences.
Fourier's masterpiece was his mathematical theory of heat conduction stated in "Theorie Analytique De La Chaleur" (1822), one of the most important books published in the 19th century. It marked an epoch both in the history of pure and of applied mathematics, for in it, Fourier developed the theory of the series known by his name and applied it to the solution of boundary-value problems in partial differential equations. This work brought to a close a long controversy, and henceforth it was generally agreed that almost any function of a real variable can be represented by a series involving the sines and cosines of integral multiples of the variable. Fourier died in Paris on May 16, 1830.