Ye Li is the main contributor to China's ancient important mathematical achievement "Tian Yuan Shu". 12 and 13 centuries, a systematic method for solving the unary equation finally appeared in northern China, that is, the famous astrology. "Tianyuan" means unknown.
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 Jiurong in the East Garden 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 astronomical art 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.
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What European mathematicians didn't finish until16th century,13rd century China has already made it. 1248, Ye Li, a mathematician in the Jin Dynasty, systematically introduced the astronomical art in the book Measuring the Circle of the Sea Mirror.
The method of sorting equations with Tianyuan is: first, set Tianyuan as Tang, that is, set unknown x now, and then list two equal Tianyuan formulas (that is, polynomials containing this Tianyuan) according to the conditions of the problem, and subtract these two Tianyuan formulas to get a Tianyuan formula, that is, a higher-order equation.
Finally, the positive root of this equation is found by increasing, multiplying and opening. Obviously, celestial sphere is similar to the formulation of algebraic equations today, but in Europe, it was not done until the sixteenth century.
In our country, solving equations is called "secret recipe". In addition to astrophysics, there is also quaternity, that is, solving quaternary higher-order equations. This was not completed in Europe until the18th century, more than 400 years later than in China.