Fourier, Jean-Baptiste Joseph, Baron (1768-1830),
French mathematician, born in Auxerre and educated at the monastery of St-Benoît-sur-Loire.
He taught (1795) at the Ecole Normale, where he had been a student, and at the
Ecole Polytechnique in Paris from 1795 to 1798, when he joined the campaign of
Napoleon in Egypt. After returning to France in 1802, he published important material
on Egyptian antiquities and was, until 1815, prefect of Isere departement. He
was created a baron by Napoleon in 1808. In 1816 he was elected to the Academy
of Sciences and in 1827 to the French Academy. His fame rests on his work in mathematics
and mathematical physics. In his treatise The Analytical Theory of Heat (1822;
trans. 1878), he employed a trigonometric series, usually called the Fourier series,
by means of which discontinuous functions can be expressed as the sum of an infinite
series of sines and cosines.
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