Mathematician:Johann Peter Gustav Lejeune Dirichlet

Full name: Johann Peter Gustav Lejeune Dirichlet.

German mathematician who worked mainly in the field of analysis.

Credited with the first formal definition of a function.

Nationality
German, although born in what was then part of the French empire.

History

 * Born: 13 Feb 1805, Düren, French Empire (now Germany)
 * Died: 5 May 1859, Göttingen, Hanover (now Germany)

Theorems

 * Dirichlet Series
 * Dirichlet's Test for Uniform Convergence