(1805 – 1859)<\/p>\r\n\r\n
Peter Gustav Lejeune Dirichlet was born in D\u00fcren, Germany on February 13, 1805. From an early age, he was fascinated by mathematics and spent his allowance on mathematics texts. Dirichlet’s parents, recognizing his extraordinary intelligence and hoping to steer him toward a career in law, sent him to excellent schools in Bonn and Cologne where he obtained a classical education. Dirichlet was an exceptionally obedient and attentive student, but was determined to be a mathematician despite his parents\u2019 objections.<\/p>\r\n\r\n
After completing his Abitur examination at the age of sixteen—well before his contemporaries—Dirichlet left Germany for Paris. There, such legendary mathematicians as Augustin-Louis Cauchy, Pierre Laplace, Sim\u00e9on Poisson, and Joseph Fourier, among others, were creating new branches of pure mathematics. Dirichlet attended lectures at the Facult\u00e9 des Sciences and the Coll\u00e9ge de France. Dirichlet met many of the country\u2019s intellectual elite through General Maximilien Fay, a French war hero whose children he tutored.<\/p>\r\n\r\n
In June 1825, at the age of twenty, Dirichlet presented his first mathematical paper to the French Academy of Sciences. Entitled M\u00e9moire sur l\u2019impossibilit\u00e9 de quelques \u00e9quations ind\u00e9termin\u00e9es du cinqui\u00e8me degr\u00e9<\/em>, the paper addressed problems in number theory devised by the ancient Greek mathematician Diophantus in about 250 a.d.<\/p>\r\n\r\n Dirichlet first became intrigued by number theory while reading Carl Gauss\u2019s Disquisitiones arithmeticae<\/em>. This remarkable work introduced many of Gauss\u2019s most significant discoveries in number theory, but was incomprehensible to most other mathematicians at that time. Dirichlet studied the book many times throughout his life, and kept a copy close at hand whenever he worked. Dirichlet\u2019s Vorlesungen \u00fcber Zahlentheorie<\/em>, published in 1863, is perhaps the best introduction to Gauss\u2019s work ever written, and amplifies Gauss\u2019s original discoveries. Despite Dirichlet\u2019s later contributions to analysis, algebraic number theory was always his favorite discipline.<\/p>\r\n\r\n Following General Fay\u2019s death in 1825, Dirichlet returned to Germany, married, and obtained a post as professor of mathematics at the University of Berlin. Dirichlet was a superb teacher who communicated difficult concepts with great clarity and insight.<\/p>\r\n\r\n His lectures, delivered during his twenty-seven years at the University of Berlin, and his many scientific papers had considerable impact on the development of mathematics in Germany. Dirichlet\u2019s proof that certain specific types of functions are the sums of their Fourier series elevated work in this field from a simple manipulation of formulas to genuine mathematics, as we understand the term today. Among his most influential works were memoirs published in 1837 and 1839, wherein he applied analysis to the theory of numbers, with spectacular results. Dirichlet\u2019s understanding of the nature of a function, that is, that for each value of x there is a unique value of y, was another important contribution to modern mathematics.<\/p>\r\n\r\n In 1855, Dirichlet left the University of Berlin for the University of G\u00f6ttingen, where a prestigious position had been left vacant by the death of Carl Gauss. Dirichlet taught at G\u00f6ttingen for three years, until suffering a heart attack in Switzerland. He had traveled to Switzerland in the summer of 1858 to speak in tribute to Gauss, but barely survived the journey back to Germany. He died at G\u00f6ttingen in May 1859, at the age of 54.<\/p>\r\n\r\n \r\nhttp:\/\/www-history.mcs.st-andrews.ac.uk\/Biographies\/Dirichlet.html<\/a>\r\nLinks<\/h3>\r\n
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