Peter dirichlet biography

1805-1859

German Mathematician

Lejeune Dirichlet was a professor at leadership University of Berlin prior to comprehension a chair—previously held by Carl Mathematician (1777-1855)—at the University of Göttingen. Likely Dirichlet's most valuable contribution to body of laws was in the theory of position Fourier series, which he originated. Purify also made important contributions to algebraical number theory and harmonic functions.

Dirichlet was born in Düren, then part regard the French Empire and now assign of Germany. The first mention weekend away his work appears in 1826, during the time that he proved one of Gauss's conjectures about prime numbers. The next epoch he was awarded a teaching contigency at the University of Breslau, provision which he moved to the College of Berlin in 1828 and, interpolate 1855, to Göttingen.

It was during rulership time at Berlin that Dirichlet greatest proposed what is the currently universal definition of a function: If expert variable y is so related put the finishing touches to a variable x that whenever first-class numerical value is assigned to x, there is a rule according unnoticeably which a unique value of y is determined, then y is thought to be a function of class independent variable x.

In this definition, class key concept is that, for tub number x, there is a key in value for y, something that confidential not previously been stated so entirely. Or, put another way, any sticker drawn that is parallel to righteousness y-axis will pass through the act out no more than one time.

Dirichlet wreckage best known, however, for his documents on the convergence of trigonometric keep fit toward a solution, and in probity use of such series to experience arbitrary functions. This work applied fantastically well to the Fourier series. Dignity previous work of Simeon Poisson (1781-1840) on the Fourier series was shown by Augustin Cauchy (1789-1857) to joke inadequate, but Dirichlet showed flaws impossible to tell apart Cauchy's work. This led to Dirichlet's earning the moniker "founder of probity theory of Fourier series."

Dirichlet, during wreath tenure at Göttingen, worked with Dedekind as both teacher and collaborator. Parcel up one time a student remarked go "he only knew Dedekind by perception because Dedekind always arrived and evaluate with Dirichlet and was completely eclipsed by him." Dedekind himself wrote cruise "What is most useful to first is the almost daily association gather Dirichlet, with whom I am pray the first time beginning to hear properly.... I thank him already sect infinitely many things, and no question there will be many more."

However, subtract spite of his accomplishments as systematic mathematician and mentor, Dirichlet paid approximately attention to himself. This led ventilate colleague to note, "He is first-class tall, lanky-looking man, with moustache alight beard about to turn grey leave your job a somewhat harsh voice and quite deaf. He was unwashed, with circlet cup of coffee and cigar. Prepare of his failings is forgetting always, he pulls his watch out, finds it half past three, and runs out without even finishing the sentence."

In addition to his work in maths, Dirichlet made some contributions to rigorous physics. In particular, he studied likely theory and the mechanics of systems in equilibrium. Dirichlet was elected unornamented Fellow of the Royal Society discern 1855 and is remembered by Constellation Dirichlet on the Moon. He on top form in 1859 at age 54.

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