Klára Dán von Neumann

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Klára Dán von Neumann
Photograph of Klara Dan von Neumann.png
Born(1911-08-18)August 18, 1911
DiedNovember 10, 1963(1963-11-10) (aged 52)
San Diego, California, United States
  • Hungarian
  • American
Known for
Scientific career
FieldsComputer science

Klára Dán von Neumann (born Klára Dán; 18 August 1911 – 10 November 1963) was a Hungarian-American self-taught computer scientist, noted as one of the first computer programmers.[2][3]

Early life[edit]

Klára Dán was born in Budapest, Hungary on August 18, 1911, to Károly Dán and Kamilla Stadler, a wealthy Jewish couple.[4][5][6] Her father had previously served in the Austro-Hungarian Army as an officer during World War I, and the family moved to Vienna to escape Béla Kun's Hungarian Soviet Republic. Once the regime was overthrown, the family moved back to Budapest. Her family was wealthy, and often held parties where Dán would meet many different people from various stations in life.

At 14, Dán became a national champion in figure skating.[5] She attended Veres Pálné Gimnázium [hu] in Budapest and graduated in 1929.[7]


After their wedding, Dán and John von Neumann immigrated to the United States, where he held a professorship at Princeton University. In 1943, von Neumann moved to Los Alamos National Laboratory in New Mexico to work on calculations as part of the Manhattan Project. Dán remained at Princeton until 1946, working at the university's Office of Population Research.[6]

After the war, Dán joined von Neumann in New Mexico to program the MANIAC I machine, which could store data, designed by her husband and Julian Bigelow.[7][8][9] She then worked on the ENIAC (Electronic Numerical Integrator and Computer) on a project with von Neumann to produce the first successful meteorological forecast on a computer. Dán designed new controls for ENIAC and was one of its primary programmers.[10][11] She trained a group of people drawn from the Manhattan Project to store programs as binary code.[6]

She taught the meteorologists how to program ENIAC where she managed 100,000 punch cards ensuring there were no data loss.[12] She worked for 32 days on the project, where she saw through and checked the final code.[3]

After her husband's death from cancer in 1957, Dán wrote the preface to his Silliman Lectures. The lectures were published in 1958[13] and later edited and published by Yale University Press as The Computer and the Brain.[14]

Personal life[edit]

Dán married Ferenc Engel in 1931 and Andor Rapoch in 1936.[15] She met Hungarian mathematician John von Neumann during a trip he made to Budapest prior to the outbreak of World War II.[16] In 1938, von Neumann's first marriage ended in a divorce, and Dán divorced Rapoch to marry him.

Dán married oceanographer and physicist Carl Eckart in 1958 and moved to La Jolla, California. She died in 1963 when she drove from her home in La Jolla to the beach and walked into the surf and drowned. The San Diego coroner's office listed her death as a suicide.[5][17]

Further reading[edit]

  • Dyson, George (2012). Turing's Cathedral: The Origins of the Digital Universe. New York: Vintage Books. ISBN 978-1-4000-7599-7. OCLC 843124457.


  1. ^ Blair Jr, Cary (25 February 1957). "Passing of a Great Mind". Time. Vol. 42, no. 8. New York: Time Inc. pp. 89–104. ISSN 0024-3019. Retrieved 31 March 2012.
  2. ^ Devlin, Keith. "John von Neumann: The Father of the Modern Computer". Mathematical Association of America.
  3. ^ a b "Weatherwatch: the unsung woman behind modern forecasting". the Guardian. 13 March 2021. Retrieved 12 August 2021.
  4. ^ Chen, J; Lu, Su-I; Vekhter, Dan. "Von Neumann and the Development of Game Theory". Retrieved 31 March 2012.
  5. ^ a b c Dyson, George (2012). Turing's Cathedral: The Origins of the Digital Universe (1st ed.). New York: Vintage Books. ISBN 978-1-4000-7599-7. OCLC 843124457.
  6. ^ a b c Witman, Sarah (16 June 2017). "Meet the Computer Scientist You Should Thank For Your Smartphone's Weather App". Smithsonian. Washington, D.C.: Smithsonian Institution. ISSN 0037-7333. Retrieved 17 February 2020.
  7. ^ a b "Finding Aid to the Collection in the Library of Congress" (PDF). John Von Neumann and Klara Dan Von Neumann Papers. Library of Congress. 2014. Retrieved 22 July 2017.
  8. ^ Kelly, Kevin (17 February 2012). "Q&A: Hacker Historian George Dyson Sits Down With Wired's Kevin Kelly". Wired. San Francisco, Calif.: Wired USA. ISSN 1078-3148. OCLC 24479723. Retrieved 22 July 2022.
  9. ^ Shepherd, Marshall. "How A Woman You Never Heard Of Helped Enable Modern Weather Prediction". Forbes. Retrieved 20 February 2020.
  10. ^ Coyle, Karen (November 2012). "Turing's Cathedral, or Women Disappear". Coyle's InFormation. Karen Coyle. Retrieved 8 December 2013.
  11. ^ Andrieu, Christophe; de Freitas, Nando; Doucet, Arnaud; Jordan, Michael I. (2003). "An Introduction to MCMC for Machine Learning" (PDF). Machine Learning. 50 (1/2): 5–43. doi:10.1023/A:1020281327116.
  12. ^ "Meet the Computer Scientist You Should Thank For Your Smartphone's Weather App". Smithsonian Magazine. Retrieved 12 August 2021.
  13. ^ von Neumann, Klara. "Preface, Von Neumann Silliman lectures". The MacTutor History of Mathematics archive. School of Mathematics and Statistics, University of St Andrews Scotland. Retrieved 31 March 2012.
  14. ^ von Neumann, John (2000). The Computer and the Brain. With a foreword by Paul M. & Patricia S. Churchland (2nd ed.). New Haven, Conn. [u.a.]: Yale Nota Bene. ISBN 9780300084733.
  15. ^ "Klára Dán". Geni Family Tree. Retrieved 22 July 2017.
  16. ^ Macrae, Norman (1992). John von Neumann: The Scientific Genius Who Pioneered the Modern Computer, Game Theory, Nuclear Deterrence, and Much More (1st ed.). New York: Pantheon Books. pp. 170–174. ISBN 978-0-6794-1308-0. OCLC 25248222.
  17. ^ "Former Wife of Late Atomic Energy Commission Official Drowns". Albuquerque Journal. 11 November 1963. Retrieved 22 July 2017.

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