Sakabe Kōhan

In this Japanese name, the family name is "Sakabe".

Sakabe Kōhan (坂部 廣胖?, 1759 – September 16, 1824) was a Japanese mathematician in the Edo period.[1]

Sakabe served for a time in the Fire Department of the shogunate, but he resigned that position to become a ronin or masterless samurai. He spent the rest of this life in study, in teaching, and in promoting mathematics education in Japan.[2]

Sakabe was a student of Ajima Naonobu.[3][4]

Sakabe investigated some European and Chinese works which had appeared in Japan, but his general a method was later construed to be innovative, clarified and thus improved.[5] Foreign influence shows itself indirectly some of his published work.[6]

Sakabe's Sampo Tenzan Shinan-roku (Treatise on Tenzan Algebra) in 1810 was the first published work in Japan proposing the use of logarithmic tables. He explained that "these tables save much labor, [but] they are but little known for the reason that they have never been printed in our country."[7] Sakabe's proposal would not be realized until twenty years after his death when the first extensive logarithmic table was published in 1844 by Koide Shuki.[8]

In Sakabe's Treatise on Tenzan Algebra, mathematical problems are arranged in order from easy problems to difficult ones. The text presents a method for finding the length of a circumference and the length an arc of an ellipse. This was the first appearance of the problems pertaining to ellipses in printed books in Japan.[9]

Selected works

In a statistical overview derived from writings by and about Harry Smith Parkes, OCLC/WorldCat encompasses roughly 10+ works in 10+ publications in 1 language and 10+ library holdings.[10]

• 1795 — Shinsen Tetsujutsu[2]
• 1802 — Kaiujutsu-keima (Considerations on the theory of the polygon)[2]
• 1803 — Rippō-eijiku, method for finding cube root[4]
• 1810 — Tenzan Shinan-roku (點竄指南錄?) OCLC 22057236896, Treatise on Tenzan Algebra[7]
• 1812 — Kwanki-kodo-shōhō, measurement of spherical arcs and trigonometrical tables[11]
• 1816 — Kairo Anshin-roku (海路安心錄?) OCLC 122810576, theory of navigation applying the spherical astronomy of the West[6]

Notes

1. ^ Smith, David. (1914). A History of Japanese Mathematics, pp. 208–213. , p. 208, at Google Books
2. ^ a b c Smith, p. 208. , p. 208, at Google Books
3. ^ Hatashi, T. [Hayashi Tsuruichi?] "The Conic Sections in the Old Japanese Mathematics," The American Mathematical Monthly, Vol. 13, No. 10 (October 1906), pp. 173–174., p. 173, at Google Books
4. ^ a b Hayashi, Tsuruichi. (1907). "A Brief history of the Japanese Mathematics," Nieuw archief voor wiskunde ("New Archive of Mathematics"), pp. 120., p. 120, at Google Books
5. ^ Smith, p. 213. , p. 213, at Google Books
6. ^ a b Smith, p. 266. , p. 266, at Google Books
7. ^ a b Smith, pp. 268–270. , p. 268, at Google Books
8. ^ Smith, pp. 268–270. , p. 270, at Google Books
9. ^ Hayashi, p. 121., p. 121, at Google Books
10. ^
11. ^ Hayashi, p. 122., p. 122, at Google Books