Person: Ajima, Chokuyen Naonobu
Naonobu Ajima was a Japanese mathematician and astronomer who developed a theory of integration.
Mathematical Profile (Excerpt):
- Ajima was over thirty years of age before he began his studies with Yamaji.
- While studying with him, Ajima wrote books on astronomy and helped his teacher to compile an almanac.
- It was only after Yamaji's death that Ajima began to write works on mathematics.
- The book had a preface written in 1799, one year after Ajima's death, by Kasawa Makoto, one of his students.
- Kasawa was a fine mathematician and he succeeded Ajima as a master of the Seki school.
- He was certainly not Ajima's only star pupil for there were also excellent mathematicians such as Masatoda Baba and Hiroyasu Sakabe who continued the tradition of the Seki school.
- Ajima's work went towards geometry despite the strong algebraic numerical tradition in the Seki school.
- Ajima refined the method subdividing the chord of an arc into equal small segments, so producing a method similar to that of the definite integral.
- Immediately after developing this method of integration, Ajima developed a method for computing volumes by double integration.
- This book introduced logarithms into Japan and it is clear that Ajima had read the work since he uses some of the same notation in his own work on logarithms.
- Let us look at two particular problems solved by Ajima.
- Although his solution was unpublished, nevertheless Ajima became famous for his work on this problem.
- Ajima's remarkable achievement was to reduce this to an equation of degree 10.
- A year after this fine achievement, Ajima was promoted to hold the position of "gun bugyou" or "country magistrate".
- It is today called the Malfatti Problem since it was posed in 1803 by Gian Francesco Malfatti, but Ajima's contributions were made around 30 years earlier.
- It is precisely the problem of maximising the area of the three mutually tangent circles that Ajima solved in Fukyu sampo.
- This, of course, is not relevant to Ajima's problem which is only posed in terms of maximising the area of three non-overlapping mutually tangent circles.
- After Ajima's death, he was buried in the Jorin-jo Temple, Mita, Tokyo, and his grave can still be visited today.
Born 1732, Shiba, Edo (now Tokyo), Japan. Died 14 November 1798, Shiba, Edo, Japan.
View full biography at MacTutor
Tags relevant for this person:
Astronomy, Origin Japan
Thank you to the contributors under CC BY-SA 4.0! 
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- non-Github:
- @J-J-O'Connor
- @E-F-Robertson
References
Adapted from other CC BY-SA 4.0 Sources:
- O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive
