Jean-Marie Duhamel

Jean-Marie Constant Duhamel (1797 to 1872) was a French mathematician and physicist, born on 5 February 1797 and died on 29 April 1872. His studies were affected by the troubles of the Napoleonic era, and he went on to form his own school, the Ecole Sainte-Barbe. Duhamel's principle, a method of obtaining solutions to inhomogeneous linear evolution equations, is named after him. He was primarily a mathematician but also studied the mathematics of heat, mechanics and acoustics, and he worked in calculus using infinitesimals; his theorem for infinitesimals says that the sum of a series of infinitesimals is unchanged by replacing each infinitesimal with its principal part. In 1853 he published on an early recording device he called a vibroscope, a measuring device that could not play back what it recorded. The asteroid 19617 Duhamel is named after him.