|Born||Carl Einar Hille
28 June 1894
New York City, United States
|Died||12 February 1980
La Jolla, California
|Alma mater||University of Stockholm|
|Doctoral advisor||Marcel Riesz|
|Doctoral students||Henri Frederic Bohnenblust
Cassius Ionescu Tulcea
Thomas L. Saaty
Carl Einar Hille (28 June 1894 – 12 February 1980) was an American mathematics professor and scholar. Hille authored or coauthored twelve books mathematical books and a number of mathematical papers 
Hille was born in New York City. 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 Ekmanto, 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 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.
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, Princeton University, Stanford University and the University of Chicago. In 1933, he became an endowed professor on mathematics in the Graduate School of Yale University. 
Hille's main work was on integral equations, differential equations, special functions, Dirichlet series and Fourier series. Later in his career his interests turned more towards functional analysis. 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. Hille served as president of the American Mathematical Society (1937–38) and was the Society's Colloquium lecturer in 1944. He received many honours including election to the United States National Academy of Sciences (1953) and the Swedish Royal Academy of Sciences. He was awarded by Sweden with the Order of the Polar Star. 
- 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.
- J J O'Connor and E F Robertson (July 2000). "Einar Carl Hille". School of Mathematics and Statistics, University of St Andrews, Scotland. Retrieved January 15, 2016.
- Ralph Phillips (1994). "Einar Hille, Biographical Memoir" (PDF). National Academy of Sciences. Retrieved January 15, 2016.
- "Einar Hille". National Academies Press. Biographical Memoirs V.63. 1994. Retrieved January 15, 2016.
- Hakan Hedenmalm. "Gösta Mittag-Leffler: A Man of Conviction" (PDF). Royal Institute of Technology, Stockholm. Retrieved January 15, 2016.
- Bertil Hille. "Bertil Hille". Society for Neuroscience. Retrieved January 15, 2016.
- Bochner, Salomon (1949). "Review: Functional analysis and semi-groups, by Einar Hille". Bull. Amer. Math. Soc. 55 (5): 528–533. doi:10.1090/s0002-9904-1949-09226-1.
- Johnson, Guy (1960). "Review: Analytic function theory, vol. 1, by Einar Hille". Bull. Amer. Math. Soc. 66 (4): 253–255. doi:10.1090/s0002-9904-1960-10444-2.
- Sibuya, Yasutaka (1977). "Review: Ordinary differential equations in the complex domain, by Einar Hille". Bull. Amer. Math. Soc. 83 (5): 935–939. doi:10.1090/s0002-9904-1977-14328-0.
- Dunford, Nelson (1981). "Einar Hille (June 28, 1894—February 12, 1980)". Bull. Amer. Math. Soc. (N.S.). 4 (3): 303–319. doi:10.1090/s0273-0979-1981-14895-3. MR 609040.
- Yosida, K. (1981). "Some aspects of E. Hille's contributions to semigroup theory". Integral Equations Operator Theory. 4 (3): 311–329. doi:10.1007/BF01697968.
- Benson, Adolph B.; Hedin, Naboth (1969). Swedes In America. New York: Haskel House.