Astrology is a general method of using unknown equations, which is basically consistent with the method of equations in modern algebra. In ancient mathematics, equation and solution are two important interrelated problems.
The word "Tianyuan" first appeared in Yi Ji Gu written by Jiang Zhou, a mathematician in the Northern Song Dynasty. Since then, Zhao Dan, Zhongjing by Shi Xindao, Confucianism, Buddhism and Taoism by Liu, and Jiuyong in Dongyuan have all expounded the "celestial art" to varying degrees. But these methods are not systematic, and they are generally discussed. The mathematicians who have made the greatest contribution to astronomy are Ye Li and Zhu Shijie. Ye Li's Round Sea Mirror, An Ancient Analysis, Zhu Shijie's Arithmetic Enlightenment and Philip Burkart's Meeting all systematically introduced the establishment of quadratic equations with celestial skill.
In the year of 1248, the monograph "Circle Measuring Sea Mirror" with volume 12 was born. From this book, word algebra evolved into symbolic algebra. The Round Sea Mirror is an elegant and authentic mathematical monograph. Its elegance has three aspects:
First of all, it is summative. The first volume of the book, Distinguishing Miscellaneous Notes, expounds the methods of finding the diameter of inscribed circle with Pythagorean strings, which are all made by pre-integral algebra. This book has more than 600 definitions and is a summary of ancient Pythagoras harmony. Starting from the second volume, he summarized an effective celestial program and answered 148 questions in 182 ways.
The second is high professionalism. The celestial theory, Pythagorean solution and the new starting point of mathematical abstraction listed in the book were all the most advanced theoretical knowledge at that time.
The third is to dare to innovate. For the convenience of calculation, the book first uses the minus sign (with a horizontal line above the number) and the symbol ○ (China number), and a set of advanced decimal notation. These are hundreds of years earlier than western mathematicians.
Li Zhi soon realized that the book "Rounding the Sea Mirror", which he had spent more than ten years writing, was too elegant and abstruse for most people to understand. How to popularize celestial magic? To this end, he is determined to write a basic reading of celestial science. After more than ten years' efforts, he finally finished the three-volume Romance of Ancient Arts. "Yi Gu" refers to Jiang Zhou's monograph One Ji Gu, and "Duan" refers to the subsection method demonstrated in One Ji Gu. The so-called slicing method is based on the method of replacing algebraic equation with geometric method in the ancient book "Nine Chapters Arithmetic", which is named because all the items in the equation are represented by strip areas. Obviously, slicing is an ancient method. Although it is intuitive, it is troublesome to calculate and takes up space. Yi Gu Yan Duan is the first theoretical work to transform the segmentation method into the art of heaven. As the preface says, "If you know a little about Pepsi, you will want to vomit in the room, so don't worry!"
The biggest feature of Yi Gu Yan Duan is to solve the problem of square and circular area in daily life with Tianshi skills. Except that the four questions are linear equations, the others are quadratic equations, and the content arrangement is basically from easy to difficult. At that time, as long as you are familiar with an ancient Yan Duan, a gourd painting can solve similar problems by listing equations. It can be said that at present, the ideas of solving quadratic equations in junior high school mathematics textbooks all come from Ye Li's An Ancient Yan Duan.
The Round Sea Mirror and An Ancient Smoke End have become the most famous novels about heaven in the world.