Born: February 9, 1880, Pécs, died: October 15, 1959 Budapest
His original name was Leopold Weiss but changed his name around 1900. In 1897 Fejér won a prize in one of the first mathematics competitions to be held in Hungary (and in the World). After that until 1902 he studied mathematics and physics at the University of Budapest and at the University of Berlin where he was a student of Schwarz.
In 1900 Fejér published his fundamental summation theorem for Fourier series (the arithmetic means of the partial sums of Fourier series of a continuous functions converge to the function) . This work was the basis of his doctoral thesis which he presented to the University of Budapest in 1902.
From 1902 to 1905 Fejér taught at the University of Budapest and from 1905 until 1911 he taught at Kolozsvár in Hungary (now Cluj in Romania). In 1911 Fejér was appointed to the chair of mathematics at the University of Budapest and he held that post until his death.
Fejér's main work was in harmonic analysis. He worked on power series and on potential theory. Much of his work is on Fourier series, trigonometric polynomials, polynomial inequalities and approximation theory.
During his life he had many students, and was a doyen of a very active and successful Hungarian school of analysis.
Biography:
http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Fejer.html
Book:
Szegö, G., The contribution of L. Fejér to the constructive function theory, in Proceedings of the Conference on Constructive Theory of Functions, edited by G. Alexitis, S. B. Stechkin, pp. 19-26, Budapest, 1972.
Article:
G. Pólya, "Leopold Fejér", Journal of the London Mathematical Society, Vol. 36., 1961. p. 501.
Link:
Birthplace of Lipót Fejér
Hermite-Fejér interpolation processes
Autorithy:
htpp://www.math.u-szeged.hu/confer/fejerriesz/Fejer.htm