1. Great mathematicians Liu Hui and Zu Chongzhi: 1. Liu Hui, a great mathematician in the Three Kingdoms period, wrote Nine Arithmetic Notes and Arithmetic on the Island. In Nine Arithmetic Notes, he created many new calculus methods, which are much simpler than the old ones. For example, he first proposed the correct calculation method of pi, which had a great influence on later Zu Chongzhi. 2. The great mathematician Zu Zu Chongzhi Chongzhi was born in Laishui County, Hebei Province today. Southern Song Dynasty, Qi Dynasty. His grandfather, Zuchang, was a senior official in charge of construction engineering in Liu, Song and Wang Dynasties. He is very good at mathematics and has a great influence on Zu Chongzhi. Zu Chongzhi is knowledgeable and versatile. He made great contributions not only in mathematics, but also in astronomical calendar and mechanical manufacturing. For example, he rewrote a calendar called "Daming Calendar", which is more accurate than other calendars according to the data of the running cycle of the sun and the moon. He determined the tropical year, that is, the time between two winter solstice points is 365.38+8+0. Compared with the results of modern astronomical science survey, there is only a gap of 50 seconds, and the relative error of one year is only one in six hundred thousand. He also reformed the jumping method. China used the method of "seven jumps in nineteen years" for a long time, which he thought was not accurate enough. After precise observation of the planet's movement and careful calculation of some mathematical values, it is considered that 144 leap months should be arranged every 39 1 year. After his death, "Da Li Ming" was officially promulgated by the Nanqi regime and has been in use for more than 80 years. He has many inventions in mechanical manufacturing. For example, according to historical records, the compass he made has the functions of "never looking back, never changing" and "never being poor, but one", but it was later lost. Encouragingly, after three years of tackling key problems, Workers' Village successfully restored Zu Chongzhi's South Compass in 1985 and 12, thus reappearing the cultural heritage lost for thousands of years. Zu Chongzhi's most important contribution to mathematics is to calculate the exact value of pi and his mathematical monograph Composition. (3) Pi and seal script circle are very important to human production and life. In daily life, we can often see and use round things. The so-called pi is the ratio of circumference to diameter. This is a fixed constant, which is the value of pi. Pi is an infinite cycle decimal. The book Parallel Calculation of Weeks compiled at the end of the Western Han Dynasty mentioned that "the diameter is three weeks", that is to say, pi is equal to 3. We call it "ancient rate". The ancient speed was very inaccurate, but it is undoubtedly a great thing that mathematicians in ancient China noticed the calculation of pi so early. Later, Liu Xin in the Western Han Dynasty, Zhang Heng in the Eastern Han Dynasty, Liu Hui in the Three Kingdoms and He Chengtian in Liu Song in the Southern Dynasties all calculated pi. Please have a look at the brief table on page 160 of the textbook. It is worth noting that Liu Hui created a method to find pi, which is called secant, and the value of pi he calculated is called Hui rate. The mathematical achievements of predecessors' research provide valuable reference for Zu Chongzhi to continue to study pi. Zu Chongzhi recalculated with the secant created by Liu Hui. The calculation tool he uses is a bamboo stick, and it takes more than 130 times to calculate the large number of nine digits, including the root, which is a very arduous task. After hard work, Zu Chongzhi finally worked out the exact value of pi. In Zu Chongzhi, he was the first mathematician in the world to calculate the value of pi to seven decimal places. His secret rate is a great discovery in the history of mathematics in the world. A thousand years later, Otto in Germany got the same value, and Antuoni in the Netherlands got the same secrecy rate. Only the Arab mathematician Al-Cassie's calculation surpassed Zu Chongzhi's. Zu Chongzhi is unknown to western mathematicians, so pi is named "Antuoni rate". In 1950s, Kazuo Sanshi, a Japanese mathematician, suggested changing pi to "ancestral rate". Scientists in the former Soviet Union named a crater on the moon Mount Zu Chongzhi. In the corridor of "Exhibition of World Great Scientists" of Moscow University, there is a colored marble statue of Zu Chongzhi. This shows that Zu Chongzhi is respected by people all over the world, and he is the glory and pride of the Chinese nation. Zu Chongzhi also compiled dozens of papers on mathematics into a book "Composition". The seal script consists of six volumes. It is a must-read for studying mathematics in Sui, Tang and Five Dynasties. In the Tang Dynasty, the state-run school opened the course of "Shu Ming", and "Zhuanshu" was listed as a mathematics textbook, and it was stipulated that it should be completed in four years. It was also used as a teaching material in Japan and Korea in the Middle Ages. This book was the highest achievement in mathematics at that time. Unfortunately, it was abandoned and lost in the Song Dynasty. Secondly, Jia Sixie and He were outstanding agronomists in the period (1), both of whom were born in Qingzhou, Shandong Province today. He lived in the Northern Wei and Eastern Wei Dynasties. He used to be the magistrate of Levin County (now northwest of Linzi). Jia Sixie lives in the Yellow River valley where the agricultural economy is developed, which is very beneficial to his agricultural research. In his preface, he said that when he compiled the Book of Qi Yao Min, he had "collected classics, poems and ballads, and asked about the age in order to test it". That is, I have extensively consulted the relevant works of predecessors and collected a large number of folk songs and Yan language; Visit experienced old farmers; Coupled with the author's own personal experience through production practice, this agricultural book was compiled. He called this book the Book of Qi Yaomin, which means "the main way of people's life". As the saying goes, food is the most important thing for the people, and the main source of food is agricultural production. Agriculture-oriented is the main line of Qi Yao Min Shu. In the early days of liberation, the state once recognized Jia Sixie as "the only pure agricultural scientist in ancient China". (2) The main contents and important contributions of the Book of Qi Yaomin. The Book of Qi Yaomin has nearly 200,000 words and is extremely rich in content. "Starting from a yeoman, I can finally stop eating sugar and finish reading books." The production experience involving agriculture, forestry, animal husbandry and by-product fishing is impressive. In agriculture, Jia Sixie emphasized the importance of soil remediation, fertilization, intensive cultivation, crop selection and crop cultivation. He knows the dialectics of agriculture very well, that is, we often say scientific farming today. For example, he pointed out that we should pay attention to the relationship between time, place and crops. It is pointed out that "the weather, location and people are harmonious, with less efforts and more success." If you do the opposite (against the objective law), you will get nothing if you work hard. "This is what we said today:' Don't lose the farming season' and' adjust measures to local conditions'. For example, he said that there was no garlic in Bingzhou, and the garlic seed taken from Chao Ge turned out to be "Bai Zi garlic", and the garlic petals became very small, while the kohlrabi from other places moved to Bingzhou for planting, and the kohlrabi became as big as a bowl. He said it was caused by different soil conditions. He also emphasized seed selection and advocated ear selection, that is, full grain, pure ear color, single harvest and single release. This is the same as the principle of the optimization method we talked about today. In a word, Jia Sixie systematically summarized the whole process of crop planting, and elaborated in detail from the aspects of land reclamation, seed selection, sowing, cultivation, soil and water conservation, harvesting and storage, which has high practical value. The Book of Qi Yao Min is the earliest and most complete agricultural book in China, and it is also one of the outstanding works in the world agricultural history. Its main contributions are as follows: First, the author has made a concrete, vivid, systematic and scientific summary of the production practice of the people of all ethnic groups in the north since the Wei and Jin Dynasties, which not only promoted the production at that time, but also played a positive role in the agricultural production of later generations. For example, in A.D. 1020, the government of the Northern Song Dynasty carved the Book of Qi Yao Min, which was given to "agricultural consultants" in various places, and people also scrambled to copy it. The agricultural books written in past dynasties paid attention to absorbing the essence of Qi Yao Min Shu. Secondly, some achievements of ancient agricultural books in China are introduced and preserved, such as the agricultural part of Miscellaneous Notes Lv Chunqiu. Another example is the Xi Sheng Shu in the Western Han Dynasty and the Moon Order for Four by Cui Ai in the Eastern Han Dynasty, both of which have been lost for a long time. Due to the citation of Qi Yaomin's Book, some contents have been preserved. Thirdly, the author collected and recorded many folk songs and agricultural proverbs, which are very precious materials for agricultural experience. Fourthly, Qi Yao Min Shu also occupies an important position in the history of world biology. For example, the principles of artificial seed selection, artificial hybridization and directional cultivation were initially revealed. British biologist Darwin was inspired by Qi Yao Min Shu.