Aida Yasuaki

Aida Yasuaki (10 February 1747 to 26 October 1817), also known as Aida Ammei, was a Japanese mathematician of the Edo period. He made significant contributions to number theory and geometry and furthered methods for simplifying continued fractions. He is also remembered for devising an original symbol for equality, which was the first appearance of a notation for equals in East Asia. His writings, published between the 1780s and 1811, include Kaisei sanpo of 1785, a set of counter-arguments against the Seiyo sanpo school, Kaiwaku sanpo of 1788, Sanpo kakujo of 1797 and Sanpo tensei-ho shinan of 1811, an introduction to his tensei method. Library catalogues record roughly fifty works by and about him.