中英雙語話中國歷史名人 第85期:劉徽

Liu Hui was a Chinese mathematician who lived in the 200s in the Wei Kingdom.

劉徽，數學家，公元200年魏晉年間人。

In 263 he published a book with solutions to mathematical problems presented in the famous Chinese book of mathematics known as Jiuzhang Suanshu or The Nine Chapters on the Mathematical Art.

公元263年，他出版了一本解決數學難題的專著——註釋《九章算術》。

In these commentaries he presented(among other things ):

在這此註釋裏，劉徽主要提出了：

An estimate of π in the comments to chapter 1. He estimated pi to 3. 141014 with a 192 sided polygon and later calculated pi as 3. 14159 by using a 3 079 sided polygon.

圓周率(第一章)劉徽算到192邊形的面積，得到π=3.141014，又算到3 079邊形的面積，得到π=3.14159。

He suggested that 3. 14 was a good approximation.

他認爲3. 14是個比較好的近似值。

His estimation is made with a method similar to Archimedes.

劉徽的計算方法與阿基米德的計算方法相似。

The Nine Chapters used the value 3 as π, but Zhang Heng had previously estimated it to the square root of 10;

《九章算術》裏的π值爲3，但是張衡原來已經算出π是10的平方根；

Gaussian elimination;

高斯消元；

Cavalieri's principle to find the volume of a cylinder.

“牟合方蓋”說。

He also presented, in a separate appendix called Haidao suanjing or The Sea Island Mathematical Manual, several problems related to surveying.

在《海島算經》中，劉徽還提出了測高測遠方法以及多次測望的方法。

Liu was one of the first mathematicians known to leave roots unevaluated, giving more exact results instead of approximations.

劉徽是最先不求解，不給近似值而給出精確值的數學家之一。