Wada Nei

Yasushi Wada (Japanese和田 宁; * 1787 in Edo, Harima Province, † 1840), or Wada Nei ( the Sino- Japanese reading of his name ), was a Japanese mathematician of the Wasan.

He was born in 1787 in Edo, and was originally called Koyama Naoaki. He first worked in the Buddhist zojoji (増 上 寺) in Edo. Finally, he left the temple and changed for unknown reasons his name in Wada Nei order. Under the patronage of Prince Tsuchimikado at the court of the Mikado, he began to deal with mathematics. He studied with Kusaka Makoto (日下 诚), a disciple Ajima Naonobus his part.

Wada Nei improved, developed by Ajima Naonobu integral calculus of Enri (円 理, dt "circle principle"). He dealt with the determination of extreme points by the Enri and provided a detailed explanation on a Seki Takakazu returning method (equivalent to the study of the zeros of the derivative). He was also the first Japanese mathematician who studied roulette curves.