Koide Chōjūrō

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, also known as Koide Shuke, was a Japanese mathematician in the Edo period. 

Koide was a student of Wada Nei.   Students of Koide included Fukuda Riken, who is also known as Fukuda Sen.

The first extensive logarithmic table was published in 1844 by Koide Shuki.    This was twenty years after the death of Sakabe Kōhan, whose Sampo Tenzan Shinan-roku (Treatise on Tenzan Algebra) in 1810 proposed the use of logarithmic tables.  Sakebe 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."   This can be explained by the conventional thinking of the period.   For example, Koide exhibited a fixed point-of-view in his preface to Tan-i sampō in 1840, explaining:
"Number dwells in the heavens and in the earth, but the arts are of human make, some being accurate and others not.   The minuteness of our mathematical work far surpasses that to be found in the West, because our power is a divine inheritance, fostered by the noble and daring spirit of a nation that is exalted over the other nations of the world." 

During the Tenpō era, Koide translated portions of Jérôme Lalande's work on astronomy.   He presented this work to the Astronomy Board as evidence of the superiority of the European calendar, but the effort produced no identifiable effect.   However, Koide's work and translations of other Western writers did indirectly affect the Tenpo calendar revision in 1842–1844.  Koide was part of the team of astronomers and mathematicians working on an improved lunar calendar system.  A great many errors had been found in the lunar calendar; and revisions were publicly adopted in 1844.  The new calendar was called the Tenpō-Jinin calendar.  It was in use in Japan until 1872 when the Gregorian calendar was adopted. 

Selected works
Koide's published writings are few. 

 1840 — Tan'i sanpō (Kenmochi Yōshichi Shōkō, ed.). 
 1897 — Sanpō tametebako (Fukuda Sen, ed.). 

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

References 
 Endō Toshisada (1896). .  Tōkyō: _____.   OCLC 122770600
 Koide, Taneo. ( 1917).   小出長十郎先生傳 (Koide Chōjūrō Sensei den).  Tokyo: 小出植男 (Tokushima-shi).  OCLC 35715221
 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
 Wiskundig Genootschap (Mathematical Society). ( 1907).    Nieuw archief voor wiskunde (New Archive of Mathematics'').  Amsterdam, Swets & Zeitlinger.    OCLC 5814818

Category:19th-century Japanese mathematicians
Category:1797 births
Category:1865 deaths
Category:Japanese writers of the Edo period