Johann Peter Gustav Lejeune Dirichlet (February 13, 1805 - May 5, 1859) was a German mathematician credited with the modern "formal" definition of a function.

His family hailed from the town of Richelet in Belgium, from which his surname "Lejeune Dirichlet" ("le jeune de Richelet" = "the young chap from Richelet") was derived, and that was where his grandfather lived.

Dirichlet was born in Düren, where his father was the postmaster. He was educated in Germany, and then France, where he learnt from many of the most renowned mathematicians of the day. His first paper was on Fermat's last theorem comprised of a partial proof for the case n = 5, which was completed by Adrien-Marie Legendre, who was one of the referees. Dirichlet also completed his own proof almost at the same time; he later also produced a full proof for the case n = 14.

He married Rebecka 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 composer Felix Mendelssohn Bartholdy.

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).

See also

• Dirichlet's theorem (number theory, 1835)
• Dirichlet characters (number theory, 1831)
• Dirichlet convolution (number theory)
• Dirichlet kernel (functional analysis, Fourier series)
• Dirichlet problem
• Dirichlet series
• Dirichlet tessellation
• Dirichlet boundary condition
• Dirichlet function
• Dirichlet distribution
• Pigeonhole principle
• Dirichlet divisor problem

External links

• Dirichlet, Johann Peter Gustav Lejeune, Vorlesungen über Zahlentheorie. Braunschweig, 1863. "Number Theory for the Millennium".
• Biography of Dirichlet found at Fermat's Last Theorem Blog

1805 births | 1859 deaths | German mathematicians | 19th century mathematicians | Number theorists

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