Carl Einar Hille (28 June 1894 – 12 February 1980) was an American mathematics professor and scholar. Hille authored or coauthored twelve mathematical books and a number of mathematical papers.

Early life and education

Hille was born in

New York City New York, often called New York City or NYC, is the most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the most densely populated major city in the Un ...

. His parents were both immigrants from Sweden who separated before his birth. His father, Carl August Heuman, was a civil engineer. He was brought up by his mother, Edla Eckman, who took the surname Hille. When Einar was two years old, he and his mother returned to Stockholm. Hille spent the next 24 years of his life in Sweden, returning to the United States when he was 26 years old. Hille entered the

University of Stockholm Stockholm University ( sv, Stockholms universitet) is a public research university in Stockholm, Sweden, founded as a college in 1878, with university status since 1960. With over 33,000 students at four different faculties: law, humanities, soci ...

in 1911. Hille was awarded his first degree in mathematics in 1913 and the equivalent of a master's degree in the following year. He received a Ph.D. from Stockholm in 1918 for a doctoral dissertation entitled ''Some Problems Concerning Spherical Harmonics''.

Career

In 1919 Hille was awarded the Mittag-Leffler Prize and was given the right to teach at the University of Stockholm. He subsequently taught at

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of high ...

Princeton University Princeton University is a private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth as the College of New Jersey, Princeton is the fourth-oldest institution of higher education in the United States and one of the ...

, Stanford University and the

University of Chicago The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private university, private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park, Chicago, Hyde Park neighborhood. The University of Chic ...

. In 1933, he became an endowed professor on mathematics in the Graduate School of

Yale University Yale University is a Private university, private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the List of Colonial Colleges, third-oldest institution of higher education in the United Sta ...

, retiring in 1962. Hille's main work was on

integral equation In mathematics, integral equations are equations in which an unknown function appears under an integral sign. In mathematical notation, integral equations may thus be expressed as being of the form: f(x_1,x_2,x_3,...,x_n ; u(x_1,x_2,x_3,...,x_n) ...

differential equation In mathematics, a differential equation is an equation that relates one or more unknown functions and their derivatives. In applications, the functions generally represent physical quantities, the derivatives represent their rates of change, an ...

special function Special functions are particular mathematical functions that have more or less established names and notations due to their importance in mathematical analysis, functional analysis, geometry, physics, or other applications. The term is defined b ...

Dirichlet series In mathematics, a Dirichlet series is any series of the form \sum_^\infty \frac, where ''s'' is complex, and a_n is a complex sequence. It is a special case of general Dirichlet series. Dirichlet series play a variety of important roles in analy ...

and Fourier series. Later in his career his interests turned more towards

functional analysis Functional analysis is a branch of mathematical analysis, the core of which is formed by the study of vector spaces endowed with some kind of limit-related structure (e.g. inner product, norm, topology, etc.) and the linear functions defined o ...

. His name persists among others in the Hille–Yosida theorem. Hille was a member of the London Mathematical Society and the

Circolo Matematico di Palermo The Circolo Matematico di Palermo (Mathematical Circle of Palermo) is an Italian mathematical society, founded in Palermo by Sicilian geometer Giovanni B. Guccia in 1884.

. Hille served as president of the

American Mathematical Society The American Mathematical Society (AMS) is an association of professional mathematicians dedicated to the interests of mathematical research and scholarship, and serves the national and international community through its publications, meetings, ...

(1947–48) and was the Society's Colloquium lecturer in 1944. He received many honours including election to the

United States National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the Nati ...

(1953) and the

Swedish Royal Academy of Sciences The Royal Swedish Academy of Sciences ( sv, Kungliga Vetenskapsakademien) is one of the royal academies of Sweden. Founded on 2 June 1739, it is an independent, non-governmental scientific organization that takes special responsibility for prom ...

. He was awarded by Sweden with the

Order of the Polar Star The Royal Order of the Polar Star ( Swedish: ''Kungliga Nordstjärneorden'') is a Swedish order of chivalry created by King Frederick I on 23 February 1748, together with the Order of the Sword and the Order of the Seraphim. The Order of t ...

Personal life

Hille was married to Kirsti Ore Hille (1906–2001) in 1937, sister of

Norwegian Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or related to Norway, a country in northwestern Europe * Norwegians, both a nation and an ethnic group native to Norway * Demographics of Norway *The Norwegian language, including ...

mathematician Øystein Ore. They had two sons, Harald and Bertil Hille.

Works

*with Ralph Phillips
''Functional Analysis and Semi-Groups.''
1948, 1957. *''Analytic Function Theory.'' 2 vols., 1959, 1964. *''Analysis.'' 2 vols., 1964, 1966. *''Lectures on Ordinary Differential Equations.'' 1969. *''Methods in Classical and Functional Analysis.'' 1972. *''Ordinary Differential Equations in the Complex Domain.'' 1976. *''In Retrospect.'' Mathematical Intelligencer, Vol.3, 1980/81, No.1, pp. 3–13.

References

Other sources

* * *

External links

* {{DEFAULTSORT:Hille, Einar 1894 births 1980 deaths 20th-century American mathematicians Mathematical analysts American people of Swedish descent Members of the United States National Academy of Sciences Order of the Polar Star Stockholm University alumni Presidents of the American Mathematical Society Members of the Royal Swedish Academy of Sciences