Marc-Antoine Parseval des Chênes (27 April 1755 – 16 August 1836) was a French

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History O ...

, most famous for what is now known as

Parseval's theorem In mathematics, Parseval's theorem usually refers to the result that the Fourier transform is unitary; loosely, that the sum (or integral) of the square of a function is equal to the sum (or integral) of the square of its transform. It originates ...

, which presaged the

unitarity In quantum physics, unitarity is the condition that the time evolution of a quantum state according to the Schrödinger equation is mathematically represented by a unitary operator. This is typically taken as an axiom or basic postulate of quantu ...

of the

Fourier transform A Fourier transform (FT) is a mathematical transform that decomposes functions into frequency components, which are represented by the output of the transform as a function of frequency. Most commonly functions of time or space are transformed, ...

. He was born in Rosières-aux-Salines, France, into an aristocratic French family, and married Ursule Guerillot in 1795, but divorced her soon after. A monarchist opposed to the

French revolution The French Revolution ( ) was a period of radical political and societal change in France that began with the Estates General of 1789 and ended with the formation of the French Consulate in November 1799. Many of its ideas are consider ...

, imprisoned in 1792, Parseval later fled the country for publishing poetry critical of the government of

Napoleon Napoleon Bonaparte ; it, Napoleone Bonaparte, ; co, Napulione Buonaparte. (born Napoleone Buonaparte; 15 August 1769 – 5 May 1821), later known by his regnal name Napoleon I, was a French military commander and political leader who ...

. Later, he was nominated to the

French Academy of Sciences The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research. It was at the ...

five times, from 1796 to 1828, but was never elected. His only mathematical publications were apparently five papers, published in 1806 as ''Mémoires présentés à l'Institut des Sciences, Lettres et Arts, par divers savants, et lus dans ses assemblées. Sciences mathématiques et physiques. (Savants étrangers.)'' This combined the following earlier monographs: # "Mémoire sur la résolution des équations aux différences partielles linéaires du second ordre," (5 May 1798). # "Mémoire sur les séries et sur l'intégration complète d'une équation aux différences partielles linéaires du second ordre, à coefficients constants," (5 April 1799). # "Intégration générale et complète des équations de la propagation du son, l'air étant considéré avec ses trois dimensions," (5 July 1801). # "Intégration générale et complète de deux équations importantes dans la mécanique des fluides," (16 August 1803). # "Méthode générale pour sommer, par le moyen des intégrales définies, la suite donnée par le théorème de M. Lagrange, au moyen de laquelle il trouve une valeur qui satisfait à une équation algébrique ou transcendante," (7 May 1804). It was in the second 1799, memoir in which he stated, but did not prove (claiming it to be self-evident), the theorem that now bears his name. He further expanded it upon his 1801 memoir, and used it to solve various

differential equation In mathematics, a differential equation is an equation that relates one or more unknown functions and their derivatives. In applications, the functions generally represent physical quantities, the derivatives represent their rates of change, an ...

s. The theorem was first printed in 1800 as a part (p. 377) of ''Traité des différences et des séries'' by Lacroix.

References

* * {{DEFAULTSORT:Parseval, Marc-Antoine 1755 births 1836 deaths 18th-century French mathematicians 19th-century French mathematicians

See also

References