Pi in China
圆周率在中国
Pi，the ratio of the circumference of a circle to its diameter, is a very im-portant constant in mathematics. The calculation of pi was an important criterion showing the development level of a nation’s mathematics in ancient times.China attained some glaring achievements in this respect.
圆周率，即圆的周长与其直径之比，是数学中最重要的常数之一。对它的计算，可以作为显示出一个国家古代数学发展的水平的尺度之一。而中国古代数学在这方面取得了令世人瞩目的成绩。
Pi was approximated in China as 3 at the beginning. Though very simple to use，the number was far from being precise.
中国古代最初把圆周率取作3，这虽应用起来简便，但太不准确。
On the journey of finding a precise pi，Liu Hui，a prominent mathematician of the Kingdom of Wei during the Three Kingdoms period，took the first crucial step by approximated pi. He did this by approximating circle polygons(plane structures，usually with three or more sides and angles that are used to help measure various aspects of shapes) via doubling the number of sides to get better approximations.He approximated pi as 3. 14.
在求准确圆周率值的征途中，首先迈出关键一步的是三国时期魏国杰出的数学家刘徽。他创立割圆术，用圆内接正多边形无限逼近圆而求取圆周率值。用这种方法他求得圆周率的近似值为3. 14。
Green is born of blue，but beats blue;the student surpasses the teacher. Lat-er, with Liu’s method，Zu Chongzhi determined pi to 7 digits.
青出于蓝，而胜于蓝。后继者祖冲之利用割圆术得出了正确的小数点后七位。
Zu Chongzhi ( 429一500 ) was a famous mathematician，astronomer and me-chanic in the Southern and Northern dynasties(421一581).Smart and fond of learning since childhood，he liked natural science，literature and philosophy, and later became a world-famous scientist.
祖冲之(429 - 500)是中国南北朝(421- 581)时著名的数学家、天文学家和机械制造家。他从小聪明好学，爱好自然科学、文学和哲学，经过刻苦的学习钻研，终于成为一位享誉世界的科学家。
The achievements Zu Chongzhi made in mathematics have been universally acknowledged. Dated as far back as 1500 years ago，He worked out an accurate value of pi. Pi is usually represented by }r, and it has always been a very important yet difficult research topic for mathematics to calculate the value of pi. Many math-ematicians of ancient China made painstaking efforts in this research with satisfac-Cory results. Based on earlier research，Zu Chongzhi continued to carry out system-atic study. After calculating more than 1,000 times，he concluded that the value of pi falls between 3. 1415926 and 3. 1415927;and therefore he became the first sci-entist in the world who calculated the value of pi to seven decimal places.Zu Chongzhi also put forward the thesis that the approximate value of pi was 355/113，which was called milu ( close ratio )，pushing the calculation of pi to a new stage.The value was the most accurate in the world at that time，and Japanese mathe-maticians respectfully called it the“Zu Chongzhi Ratio”.Not until more than 1,000 years later, did scientists in the West come up to and surpass the achievements of Zu Chongzhi.
祖冲之在数学方面的成就为世界所公认。远在1500多年前，祖冲之就计算出了精确的圆周率。。圆周率通常用“∏”来表示，求算圆周率的值是数学中一个非常重要也是非常困难的研究课题。中国古代许多数学家都为研究这个课题付出了心血，并取得了喜人的成果。祖冲之在前人研究的基础上，继续进行了深人系统的研究，经过1000多次的计算，得出圆周率在3.1415926和3.1415927之间，成为世界上第一个把圆周率推算到小数点后七位数字的科学家。祖冲之还提出二的近似值为355/113，称为“密率”，把数学中关于圆周率的计算推进到一个新阶段，成为当时世界上最精确的圆周率。日本数学家尊称它为“祖率”。直到1000多年以后，西方的数学家才达到和超过了祖冲之的成就。