science · 08 December 1865 · 159 years ago
birth
Born 8 Dec 1865; died 17 Oct 1963 at age 97.
French mathematician who proved the prime-number theorem (as n approaches infinity, the limit of the ratio of (n) and n/ln n is 1, where (n) is the number of positive prime numbers not greater than n). Conjectured in the 18th century, this theorem was not proved until 1896, when Hadamard and also Charles de la Vallée Poussin, used complex analysis. Hadamard's work includes the theory of integral functions and singularities of functions represented by Taylor series. His work on the partial differential equations of mathematical physics is important. He introduced the concept of a well-posed initial value and boundary value problem. In considering boundary value problems he introduced a generalisation of Green's functions (1932).
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