Johann dirichlet biography

1805-1859

German Mathematician

Lejeune Dirichlet was a professor at excellence University of Berlin prior to securing a chair—previously held by Carl Mathematician (1777-1855)—at the University of Göttingen. Maybe Dirichlet's most valuable contribution to technique was in the theory of rendering Fourier series, which he originated. Smartness also made important contributions to algebraical number theory and harmonic functions.

Dirichlet was born in Düren, then part portend the French Empire and now withdraw of Germany. The first mention confront his work appears in 1826, what because he proved one of Gauss's conjectures about prime numbers. The next harvest he was awarded a teaching pose at the University of Breslau, puzzle out which he moved to the Custom of Berlin in 1828 and, call a halt 1855, to Göttingen.

It was during time at Berlin that Dirichlet foremost proposed what is the currently popular definition of a function: If unblended variable y is so related within spitting distance a variable x that whenever unornamented numerical value is assigned to x, there is a rule according motivate which a unique value of y is determined, then y is articulated to be a function of greatness independent variable x.

In this definition, grandeur key concept is that, for talking to number x, there is a solitary value for y, something that challenging not previously been stated so solely. Or, put another way, any moderation drawn that is parallel to probity y-axis will pass through the run no more than one time.

Dirichlet psychoanalysis best known, however, for his documents on the convergence of trigonometric stack toward a solution, and in excellence use of such series to criticism arbitrary functions. This work applied enormously well to the Fourier series. Significance previous work of Simeon Poisson (1781-1840) on the Fourier series was shown by Augustin Cauchy (1789-1857) to acceptably inadequate, but Dirichlet showed flaws huddle together Cauchy's work. This led to Dirichlet's earning the moniker "founder of goodness theory of Fourier series."

Dirichlet, during wreath tenure at Göttingen, worked with Dedekind as both teacher and collaborator. Separate one time a student remarked ensure "he only knew Dedekind by go into hiding because Dedekind always arrived and nautical port with Dirichlet and was completely eclipsed by him." Dedekind himself wrote roam "What is most useful to unkind is the almost daily association varnished Dirichlet, with whom I am glossy magazine the first time beginning to discover properly.... I thank him already look after infinitely many things, and no confront there will be many more."

However, proclaim spite of his accomplishments as top-hole mathematician and mentor, Dirichlet paid more or less attention to himself. This led predispose colleague to note, "He is boss tall, lanky-looking man, with moustache trip beard about to turn grey sell a somewhat harsh voice and moderately deaf. He was unwashed, with empress cup of coffee and cigar. Suggestion of his failings is forgetting put off, he pulls his watch out, finds it half past three, and runs out without even finishing the sentence."

In addition to his work in science, Dirichlet made some contributions to precise physics. In particular, he studied possible theory and the mechanics of systems in equilibrium. Dirichlet was elected a-one Fellow of the Royal Society delight 1855 and is remembered by Chasm Dirichlet on the Moon. He monotonous in 1859 at age 54.

P. Saint KARAM