Paul Émile Appell
French mathematician (1855–1930)
- 2 min read
- 2 chapters
Related on Lably
Through Paris, Differential equation and Real number
- M. P. Appell is the same person: it stands for Monsieur Paul Appell.
Life
Paul Appell entered the École Normale Supérieure in 1873. He was elected to the French Academy of Sciences in 1892.
In 1895, he became a Professor at the École Centrale Paris. Between 1903 and 1920 he was Dean of the Faculty of Science of the University of Paris, then Rector of the University of Paris from 1920 to 1925.
Appell was the President of the Société astronomique de France (SAF), the French astronomical society, from 1919 to 1921.
His daughter Marguerite Appell (1883–1969), who married the mathematician Émile Borel, is known as a novelist under her pen-name Camille Marbo.
Appell was an atheist. He was awarded Order of the White Eagle. and was also elected to honorary membership of the Manchester Literary and Philosophical Society.
Sign in to keep reading
One more chapter is free with a Lably account.
Work
He worked first on projective geometry in the line of Chasles, then on algebraic functions, differential equations, and complex analysis. Appell was the editor of the collected works of Henri Poincaré. Jules Drach was co-editor of the first volume.
Appell series
He introduced a set of four hypergeometric series F1, F2, F3, F4 of two variables, now called Appell series, that generalize Gauss's hypergeometric series.
He established the set of partial differential equations of which these functions are solutions, and found formulas and expressions of these series in terms of hypergeometric series of one variable. In 1926, with Professor Joseph-Marie Kampé de Fériet, he authored a treatise on generalized hypergeometric series.
Mechanics
In mechanics, he proposed an alternative formulation of analytical mechanics known as Appell's equation of motion.
He discovered a physical interpretation of the imaginary period of the doubly periodic function whose restriction to real arguments describes the motion of an ideal pendulum.