Jacques Hadamard

Jacques Salomon Hadamard (French: [adamaʁ]; 8 December 1865 – 17 October 1963) was a French mathematician who made major contributions in complex analysis, number theory, differential geometry, and partial differential equations.

Biography

The son of a teacher, Amédée Hadamard, of Jewish descent, and Claire Marie Jeanne Picard, Hadamard was born in Versailles, France and attended the Lycée Charlemagne and Lycée Louis-le-Grand, where his father taught. In 1884 Hadamard entered the École Normale Supérieure, having placed first in the entrance examinations both there and at the École Polytechnique. His teachers included Tannery, Hermite, Darboux, Appell, Goursat, and Picard. He published his famous thesis in 1892 containing the Hadamard gap theorem, the Cauchy–Hadamard theorem, Hadamard's theorem on the radius of meromorphy and the Hadamard fractional integral. Later that year, he was awarded the Grand Prix des Sciences Mathématiques for a memoir containing the Hadamard factorization theorem that applies it and the results of his thesis to the Riemann zeta function.

In 1892, Hadamard married Louise-Anna Trénel, also of Jewish descent, with whom he had three sons and two daughters. The following year he took up a lectureship in the University of Bordeaux, where he proved his celebrated inequality on determinants, which led to the discovery of Hadamard matrices when equality holds. In 1896 he made two important contributions: he proved the prime number theorem, using complex function theory (also proved independently by Charles Jean de la Vallée-Poussin); and he was awarded the Bordin Prize of the French Academy of Sciences for his work on geodesics in the differential geometry of surfaces and dynamical systems. In the same year he was appointed Professor of Astronomy and Rational Mechanics in Bordeaux.