Ajima Naonobu

Ajima Naonobu
Born	1732
Died	May 20, 1798
Nationality	Japanese
Occupation	mathematician
Known for	Credited with introducing calculus into Japanese mathematics

In this Japanese name, the surname is Ajima.

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]

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]

This is a dynamic list and may never be able to satisfy particular standards for completeness. You can help by adding missing items with reliable sources.

• 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

• Sangaku, the custom of presenting mathematical problems, carved in wood tablets, to the public in shinto shrines
• Soroban, a Japanese abacus
• Japanese mathematics

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

• Endō Toshisada (1896). History of mathematics in Japan (日本數學史史, Dai Nihon sūgakush). Tōkyō: _____. OCLC 122770600
• Oya, Shin'ichi. (1970). "Ajima Naonobu" in Dictionary of Scientific Biography, Vol. 1. New York: Charles Scribner's Sons. ISBN 0-684-10114-9
• Restivo, Sal P. (1992). Mathematics in Society and History: Sociological Inquiries. Dordrecht: Kluwer Academic Publishers. ISBN 978-0-7923-1765-4; OCLC 25709270
• Selin, Helaine. (1997). Encyclopaedia of the History of Science, Technology, and Medicine in Non-Western Cultures. Dordrecht: Kluwer/Springer. ISBN 978-0-7923-4066-9; OCLC 186451909
• David Eugene Smith and Yoshio Mikami. (1914). A History of Japanese Mathematics. Chicago: Open Court Publishing. OCLC 1515528 -- note alternate online, full-text copy at archive.org