π

As soon as I mentioned the concept of Pi (π) amongst ancient civilizations a few days ago, I could not resist the temptation to look up the topic again.

The official record is straightforward. The first rigorous algorithm for the calculation of π was a geometrical approach using polygons, devised by Archimedes. Possibly by coincidence, ancient Chinese mathematicians used the same approach in the following centuries. For example, Liu Hui (劉徽) if the Wei Empire (魏) created a polygon-based iterative algorithm - some 500 years after Archimedes - and used it with a 3072-sided polygon to obtain the value of π. Another 200 years later, Zu Chongzhi (祖沖之) used the same algorithm of Liu Hui and applied it to a 12288-sided polygon.

But, the controversy is no one seems to be very sure how Zu calculated his π.

PS. Zu actually described in details his methods in the book Zhui Shu (綴術) (literally The Method of Interpolation) - the textbook on mathematics once used by the Tang Empire in the National Academy (國子監). The black humor is Zhui Shu was too difficult to be understood by students and was therefore removed from the syllabus after a few years.