Posted: Tuesday, July 10, 2018

Mohammad K. Azarian, University of Evansville professor of mathematics,  published a paper entitled, Risala al-watar wa'l jaib ("The Treatise on the Chord and Sine")-Revisited, in Forum Geometricorum.

The purpose of this paper was three-fold. First, Azarian used Jamshid al-Kashi's [Kashani's] famous cubic equation and a mathematica program to calculate sine of one degree to over 11,200,000 decimal digits of accuracy; an amazing improvement over the 17 digits of accuracy that Kashani found by pencil and paper in 1426. Then, Azarian conjectured that Kashani's cubic equation can be used to calculate sine of one degree to any desired accuracy. Second, Azarian set the record straight about the number of correct digits obtained by Kashani that were reported in many previous studies. Third, Azarian commented on some statements that he made in his previous paper on this topic.