Ajima Naonobu

Ajima Naonobu (安島 直円, 1732 – May 20, 1798), also known as Ajima Manzō Chokuyen, was a Japanese mathematician of the Edo period.[1]

Ajima Naonobu
Born1732
DiedMay 20, 1798
NationalityJapanese
Occupationmathematician
Known forCredited with introducing calculus into Japanese mathematics
In this Japanese name, the surname is Ajima.

His Dharma name was (祖眞院智算量空居士).[2]

Work

Ajima is credited with introducing calculus into Japanese mathematics. The significance of this innovation is diminished by a likelihood that he had access to European writings on the subject.[3] Ajima also posed the question of inscribing three mutually tangent circles in a triangle;[4] these circles are now known as Malfatti circles after the later work of Gian Francesco Malfatti, but two triangle centers derived from them, the Ajima–Malfatti points, are named after Ajima.[5][6]

Ajima was an astronomer at the Shogun's Observatory (Bakufu Temmongaki).[7]

Legacy

In 1976, the International Astronomical Union (IAU) honored Ajima by identifying a crater on the Moon with his name. Naonobu is a small lunar impact crater located on the eastern Mare Fecunditatis, to the northwest of the prominent crater Langrenus.[8][9]

Selected works

In a statistical overview derived from writings by and about Ajima Naonobu, OCLC/WorldCat encompasses roughly 20+ works in 30+ publications in two languages and 40+ library holdings.[10]

  • Ajima Naonobu zenshū (安島直円全集) OCLC 017232052, collected works
  • Sanpō kosō (算法考艸) OCLC 057185881, algorithms considered
  • Jujireki bimmo (Introduction of the 'Works and Days Calendar')[7]
  • Anshi seiyo-reki koso (Ajima's Studies for Western Calendars)[7]
  • Ajima sensei bimmo do jutsu (Methods of Professor Ajima's 'bimmo')[7]
  • Koshoku mokyu zokkai (Introduction of Eclipses of the Sun and the Moon)[11]
  • Sansha San'en Jutsu (Methods of Three Diagonals and Three Circles)[12]
  • Fujin Isshũ (Periods of Decimal Fractions)[1]

See also

Notes
  1. Smith, David. (1914). A History of Japanese Mathematics, pp. 195-205., p. 195, at Google Books
  2. "名墓録". 矢島俯仰 (in Japanese). Retrieved 2019-10-18.
  3. Restivo, Sal P. (1992). Mathematics in Society and History: Sociological Inquiries, p. 58. , p. 58, at Google Books
  4. Fukagawa, Hidetoshi; Rothman, Tony (2008), Sacred mathematics: Japanese temple geometry, Princeton University Press, p. 79, ISBN 978-0-691-12745-3.
  5. Weisstein, Eric W. "Ajima-Malfatti Points". MathWorld..
  6. C. Kimberling, Encyclopedia of Triangle Centers Archived 2012-04-19 at the Wayback Machine, X(179) and X(180).
  7. Jochi, Shigeru. (1997). "Ajima Naonobu," Encyclopaedia of the History of Science, Technology, and Medicine in Non-Western Cultures, p. 38., p. 38, at Google Books
  8. United States Geological Survey: Naonobu Gazetteer of Planetary Nomenclature, International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN)
  9. "Naonobu lunar crater (in Japanese)". Archived from the original on 2007-12-21. Retrieved 2004-07-19.
  10. WorldCat Identities Archived 2010-12-30 at the Wayback Machine: 安島直円 1739-1798
  11. Jochi, pp. 38-39., p. 38, at Google Books
  12. Jochi, p. 39., p. 39, at Google Books

References
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