Posted: 23/June/2006 at 23:01 | IP Logged

Zu Chongzhi the Mathematician and Astronomer 
 

To calculate the accurate value of the ratio of the circumference of a circle to its diameter has always been an important but difficult subject in mathematics. Many mathematicians Chinese and abroad have been working on it. The result got by Chinese mathematician Zu CHongzhi, or Tsu Ch'ungChi, could be said a giant leap forward for the research.

Zu Chongzhi was born into an extremely talented family with successive generations being astronomer and with special interests in calander and mathematics. Zu Chongzhi, in the family tradition, was taught a variety of skills as he grew up, especially the mathematical and astronomical skills and the science of the calendar in particular. He began his computing on the value of the ratio of the circumference of a circle to its diameter at the age of 35.

In ancient China, people had already learned from expirence that the value of the circumference of a circle is a little more than three time its diameters. But exactly how much more, no one knows. A scientist before Zu Chongzhi, Liu Hui approximated it to four decimal places. Zu Chongzhi devised a precise method of calculate and finally found the precise value of the ratio of the circumference of a circle to its diameter is as 355 to 113. He approximated the value to seven decimal places.

What extremely lengthy calculations he had undertaken to find this we would never know. But Zu's work was considered very difficult and advanced by scientists worldwide. The value was also found by a scientist outside China only a thousand years later.

In the latter part of his life, Zu Chongzhi collaborated with his son and devised the calculation method on the volume of sphere, a method coincides with the Cavalieri theory, which was found by the Italian scientist Cavalieri one thousand years later.

In 656, after editing by Li Chunfeng, the treatise Zhui shu (Method of Interpolation) became a text for the Imperial examinations and it became one of The Ten Classics when reprinted in 1084. However, the Zhui shu was too advanced for the students at the Imperial Academy and it was dropped from the syllabus for that reason. This almost certainly explains why the text has not survived, being lost in the early twelfth century.(Source: CRI)