Lejeune Dirichlet  

Johann Peter Gustav Lejeune Dirichlet


Born  13
February 1805 Düren, French Empire 
Died  5
May 1859 (aged 54) Göttingen, Hanover 
Residence  Germany 
Nationality  German 
Fields  Mathematician 
Institutions  University of Berlin University of Breslau University of Göttingen 
Alma mater  University of Bonn 
Doctoral advisor  Simeon Poisson Joseph Fourier 
Doctoral students  Ferdinand
Eisenstein Leopold Kronecker Rudolf Lipschitz Carl Wilhelm Borchardt 
Known for  Dirichlet function Dirichlet eta function 
Johann Peter Gustav Lejeune Dirichlet (German pronunciation: [ləˈʒœn diʀiˈkleː]; 13 February 1805 – 5 May 1859) was a German mathematician credited with the modern formal definition of a function.
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His family was from Richelette, a small community 5 km north east of Liège in Belgium, from which his surname "Lejeune Dirichlet" ("le jeune de Richelette", French for "the youth from Richelette") was derived.^{[1]}
Dirichlet was born in Düren, where his father was the postmaster. He learned from Georg Ohm at the Jesuit gymnasium in Cologne. His first paper was on Fermat's last theorem comprising a partial proof for the case n = 5, which was completed by AdrienMarie Legendre, one of the referees. Dirichlet completed his own proof almost at the same time; later he produced a full proof for the case n = 14.
He graduated from the University of Bonn in 1827 and taught as a Privatdozent at the University of Breslau, later teaching at the University of Berlin. In 1855 Dirichlet began teaching at the University of Göttingen. In 1854, he was elected a foreign member of the Royal Swedish Academy of Sciences.
In 1831, he married Rebecca Henriette Mendelssohn Bartholdy, who came from a distinguished family of converts from Judaism to Christianity; she was a granddaughter of the philosopher Moses Mendelssohn, daughter of Abraham Mendelssohn Bartholdy and a sister of the composers Felix Mendelssohn Bartholdy and Fanny Mendelssohn.
Ferdinand Eisenstein, Leopold Kronecker, and Rudolf Lipschitz were his students. After his death, Dirichlet's lectures and other results in number theory were collected, edited and published by his friend and fellow mathematician Richard Dedekind under the title Vorlesungen über Zahlentheorie (Lectures on Number Theory).
