Peter Gustav Lejeune Dirichlet

Peter Gustav Lejeune Dirichlet
Peter Gustav Lejeune Dirichlet
Born	(1805-02-13)13 February 1805 Düren, French Empire
Died	5 May 1859(1859-05-05) (aged 54) Göttingen, Hanover
Residence	Prussia
Nationality	German
Fields	Mathematician
Institutions	University of Wrocław University of Berlin University of Göttingen
Academic advisors	Siméon Poisson Joseph Fourier Carl Gauss
Doctoral students	Gotthold Eisenstein Leopold Kronecker Rudolf Lipschitz Carl Wilhelm Borchardt
Other notable students	Moritz Cantor Elwin Bruno Christoffel Richard Dedekind Alfred Enneper Eduard Heine Bernhard Riemann Ludwig Schläfli Ludwig von Seidel Wilhelm Weber Julius Weingarten
Known for	See full list
Notable awards	PhD (Hon): University of Bonn (1827) Pour le Mérite (1855)

Johann Peter Gustav Lejeune Dirichlet (German: [ləˈʒœn diʀiˈkleː] or [ləˈʒœn diʀiˈʃleː]; 13 February 1805 – 5 May 1859) was a German mathematician who made deep contributions to number theory (including creating the field of analytic number theory), and to the theory of Fourier series and other topics in mathematical analysis; he is credited with being one of the first mathematicians to give the modern formal definition of a function.

Gustav Lejeune Dirichlet was born on 13 February 1805 in Düren, a town on the left bank of the Rhine which at the time was part of the First French Empire, reverting to Prussia after the Congress of Vienna in 1815. His father Johann Arnold Lejeune Dirichlet was the postmaster, merchant, and city councilor. His paternal grandfather had come to Düren from Richelette (or more likely Richelle), a small community 5 km north east of Liège in Belgium, from which his surname "Lejeune Dirichlet" ("le jeune de Richelette", French for "the young from Richelette") was derived.

Although his family was not wealthy and he was the youngest of seven children, his parents supported his education. They enrolled him in an elementary school and then private school in hope that he would later become a merchant. The young Dirichlet, who showed a strong interest in mathematics before age 12, convinced his parents to allow him to continue his studies. In 1817 they sent him to the Gymnasium Bonn () under the care of Peter Joseph Elvenich, a student his family knew. In 1820 Dirichlet moved to the Jesuit Gymnasium in Cologne, where his lessons with Georg Ohm helped widen his knowledge in mathematics. He left the gymnasium a year later with only a certificate, as his inability to speak fluent Latin prevented him from earning the Abitur.