Yang Hui
Yang Hui (flourished c. 1261â75, Qiantang, Zhejiang province, China) was a mathematician active in the great flowering of Chinese mathematics during the Southern Song dynasty.
Although practically nothing is known about the life of Yang, his books are among the few contemporary Chinese mathematics works to survive. A remark in the preface to one of his treatises indicates that he was a mandarin (scholar-official).
Yangâs works are mentioned in the Wenyan ge shumu (1441; âCatalogue of the Books of the Ming Imperial Libraryâ) but were long thought to be irreparably lost. Ruan Yuan, compiler of Chou ren zhuan (1799; âBiographies of Mathematicians and Astronomersâ), first found fragments of Yangâs Xiangjie jiuzhang suanfa (1261; âA Detailed Analysis of the Nine Chapters on the Mathematical Proceduresâ) in a handwritten copy of an imperial Ming dynasty encyclopaedia, and he later discovered in Suzhou a Song dynasty edition of Yang Hui suanfa (1275; âYang Huiâs Mathematical Methodsâ). The latter contains three treatises, Chengchu tongbian benmo (1274; âFundament and Periphery for Continuity and Change in Multiplication and Divisionâ), Tianmu bilei chengchu jiefa (1275; âQuick Methods for Multiplication and Division in Surveying and Analogous Categoriesâ), and Xu gu zhai qi suan fa (1275; âSelection of Strange Mathematical Methods in Continuation of Antiquityâ). A collected edition (1378) of these works was transmitted farther to the east, where it was particularly influential. In Korea it was reprinted during the reign of Sejong in 1433, and it was copied again by the Japanese mathematician Seki Takakazu (c. 1640â1708). Of another work, Riyong suanfa (1262; âMathematical Methods for Daily Useâ), only the preface and a few problems are known.
Yangâs Jiuzhang suan fa zuan lei (c. 1275; âReclassification of the Mathematical Procedures in the Nine Chaptersâ)âa compilation and reclassification, with further explanations, of the problems from the Han dynasty classic and its commentaries, Jiuzhang suanshu (c. 100 bcâad 50; Nine Chapters on the Mathematical Procedures)âcontains the oldest representation of what is known in the West as Blaise Pascalâs triangle (see the ; see also binomial theorem). In the preface Yang asserts that he copied it from an older explication, Huangdi jiuzhang suanfa (âYellow Emperorâs Nine Chapters on Mathematical Methodsâ) by Jia Xian (flourished c. 1050).
Yangâs âMathematical Methodsâ was compiled with a pedagogic perspective. In the beginning of his book, he gives recommendations for the study of mathematics: start from the multiplication table, called â9 9 81â in the Chinese tradition, then study the positions for layout of numerals and the multiplication algorithms for higher numbers. In his collection he also describes in detail a geometric method for solving quadratic equations. A variety of magic squares can be found in âStrange Mathematical Methods,â including a 10-by-10 square such that each vertical and horizontal line of numbers adds to 505.
