Jacques HadamardJacques Solomon Hadamard (December 8, 1865 - October 17, 1963 ) was one of the mathematicians who proved the prime number theorem.
He studied at the École Normale Supérieure.
After the Dreyfus affair, which involved him personally, he became politically active and became a staunch supporter of Jewish causes.
He introduced the idea of well-posed problem in the theory of partial differential equations. He also gave his name to the Hadamard inequality on volumes, and the Hadamard matrix.
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