Johann Peter Gustav Lejeune Dirichlet

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 D?ren, 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. This was a famous conjecture (now proven) that stated that for n > 2, the equation xn + yn = zn has no integer solutions, apart from the trivial ones in which x, y, or z is zero. He produced 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 Rebecca Mendelssohn, who came from a distinguished Jewish family, being a granddaughter of the philosopher Moses Mendelssohn, and a sister of the composer Felix 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 ?ber Zahlentheorie (Lectures on Number Theory).

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

February 13: February 13 is the 44th day of the year in the Gregorian calendar. There are 321 days remaining, 322 in leap years....

1805: 1805 was a common year starting on Tuesday (see link for calendar)....

May 5: May 5 is the 125th day of the year in the Gregorian Calendar (126th in leap years). There are 240 days remaining....

Johann Peter Gustav Lejeune Dirichlet related Images and Photos (experimental)

Peter Pan	Peter Pan	Peter Falk	Peter Cook
Peter Fonda	Gustav Mahler	Peter Budaj	Peter Lupus
Peter Finch	Peter Andre	Peter Budaj	Peter Noone