History 430AD

430 A.D.
Contributions from Charles and Fili

Tsu Ch'ung Chi was born in Fan-yang, China in 430 AD. He was an astronomer, engineer and mathematician. In astronomy, he recommended a new calendar that he made in 463. He also found an accurate time of the solstice by measuring the length of the Sun's shadow at noon around the time of the solstice. In mathematics he found a rational approximation 355/113 = 3.14159265 to pi (3.1415927…). This is correct for six decimal places. Not much is known about his approximation because his book, written by his son is now lost. Tsu Ch'ung Chi and his father found the formula for the volume of a sphere by carrying out Liu Hui's suggestion.

Author: Charles DeBoer

References:
http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Tsu.html
JOC/EFR December 1996

http://www.bmwf.gv.at/1bm/texts/95-2/9math.htm

http://aleph0.clarku.edu/~djoyce/mathhist/china.math, Outline of the History of Chinese Mathematics
Mathematics 105, History of Mathematics, Clark University, Worcester, MA 01610, Fall 1994, D Joyce

Chinese mathematicians have contributed vastly to our current knowledge of Math. Perhaps one of the least mentioned for his work is Tsu Ch'ung Chi. A mathematician and astronomer between 430-501 AD, Chi calculated the rational approximation of 355/113 to Pi. His estimation
is accurate to 6 decimal places. Furthermore, Chi also proved that 3.1415926<Pi<3.1415927. However, little details about how he actually came to that result is lost. He wrote his "lost book" with his son. In astronomy, Chi produced a new calendar which was never put to use. Finally, Tsu calculated the time of the soltice with great precision. This perhaps lead modern astronomers to name a crater on the moon after Chi.

Author: Filiberto Barajas

References:
1.Biography in Dictionary of Scientific Biography (New York 1970-1990)

Articles:
2.U Libbrecht, Chinese Mathematicians in the 13th Century (Cambridge, Mass, 1973), 275-276.
3.Y-L Zha, Research on Tsu Ch'ung-Chih's approximate method for Pi, in Science and Technology in Chinese Civilization. (Teaneck, NJ, 1987), 77-85.

URL:
http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/Tsu.html

Last updated December 1998