Li Rui (mathematician)

Li Rui (李銳) (born 1768, died 1817) was a prominent Chinese mathematician, astronomer, and cartographer of the Qing Dynasty. He is best known for his contributions to Euclidean geometry, trigonometry, and solving higher-order equations.

Li Rui was part of the Huang Qing Jingjie (皇清經解) project, a massive scholarly undertaking during the reign of the Qianlong Emperor. He studied mathematics under Mei Wending's grandson, Mei Juecheng, and later served in the Qing government as an official, further developing his mathematical skills and knowledge.

His most important work is considered to be Ce Yuan Hai Jing Shi Cao (測圓海鏡釋草), a detailed commentary and explanation of Li Zhi's (李冶) Ce Yuan Hai Jing (測圓海鏡), a work on solving algebraic equations using geometrical methods. Li Rui's commentary significantly clarified and expanded upon Li Zhi's original text, making it more accessible to later generations of mathematicians.

Li Rui also made important contributions to trigonometry. He compiled trigonometric tables and developed methods for solving trigonometric problems. His work in this area helped to advance the understanding and application of trigonometry in China.

Furthermore, Li Rui was involved in surveying and cartography, applying his mathematical knowledge to practical problems such as land surveying and mapmaking. He played a role in creating accurate maps of various regions of China.

Li Rui's work was instrumental in reviving and promoting the study of traditional Chinese mathematics during the Qing dynasty. He is considered one of the most important mathematicians of that era, and his contributions continue to be studied and appreciated today.