Naonobu Ajima studied under Masatada in the Nakanishi school. After this he studied mathematics and astronomy under Yamaji becoming a pupil of the Seki school.
He published nothing in his lifetime but his main work Fukyu sampo had a preface written in 1799, one year after Ajima's death, by Kasawa, one of his students. Although the intention was to publish the work then, it did not happen.
Ajima's work went towards geometry despite the strong algebraic numerical tradition in the Seki school. He developed methods of computing volumes by double integration and worked on logarithms.
In particular he produced log tables which were designed for taking 10th roots and powers of numbers. For this purpose he set the log of the 10th root of 10 to 1. His methods for calculating lengths of arcs of circles were more sophisticated than the Greek methods of Archimedes.
Article by: J J O'Connor and E F Robertson
February 1997