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。对它的计算出来，可以作为表明出有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获得了令世人注目的成绩。

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，这虽应用于一起简单，但过于不精确。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.在欲精确圆周率值的征途中，首先迈进关键一步的是三国时期魏国卓越的数学家刘徽。

他创办阴圆术，用圆内相接正多边形无限迫近圆而贪图圆周率值。用这种方法他求出圆周率的近似值为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。后继者祖冲之利用阴圆术得出结论了准确的小数点后七位。

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)时知名的数学家、天文学家和机械制造家。他自小聪慧好学，嗜好自然科学、文学和哲学，经过勤奋的自学钻研，再一沦为一位享有盛名世界的科学家。

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普遍认为。远在1500多年前，祖冲之就计算出来出有了准确的圆周率。圆周率一般来说用“∏”来回应，求算圆周率的值是数学中一个十分最重要也是十分艰难的研究课题。中国古代许多数学家都为研究这个课题代价了心血，并获得了喜人的成果。

祖冲之在前人研究的基础上，之后展开了浅人系统的研究，经过1000多次的计算出来，得出结论圆周率在3.1415926和3.1415927之间，沦为世界上第一个把圆周率推算出到小数点后七位数字的科学家。祖冲之还明确提出二的近似值为355/113，称作“密率”，把数学中关于圆周率的计算出来前进到一个新阶段，沦为当时世界上最准确的圆周率。日本数学家敬称它为“祖率”。

直到1000多年以后，西方的数学家才超过和多达了祖冲之的成就。

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