Pierre de Fermat

Pierre de Fermat, who lived from 17 August 1601 to 12 January 1665, was a French magistrate, polymath and mathematician credited with early developments that led to infinitesimal calculus, including his technique of adequality. He made notable contributions to number theory, analytic geometry, probability and optics, and is best known for Fermat's principle of light propagation and for Fermat's Last Theorem. Born in Beaumont-de-Lomagne in Gascony, he worked as a lawyer and councillor at the parlement of Toulouse and mathematics was more a hobby than a profession for him. For computing, the relevant part of his work is number theory: he invented a factorization method that bears his name, which writes an odd integer as a difference of two squares, and he popularized the proof by infinite descent.