Li Rui (; 8 December 1768 in

Suzhou Suzhou (; ; Suzhounese: ''sou¹ tseu¹'' , Mandarin: ), alternately romanized as Soochow, is a major city in southern Jiangsu province, East China. Suzhou is the largest city in Jiangsu, and a major economic center and focal point of trade ...

– 30 June 1817 in Suzhou) was a Chinese mathematician. Li discovered independently an equivalent version of what is known today as

Descartes' rule of signs In mathematics, Descartes' rule of signs, first described by René Descartes in his work ''La Géométrie'', is a technique for getting information on the number of positive real roots of a polynomial. It asserts that the number of positive roots i ...

References

*Joseph Warren Dauben and Christoph J. Scriba, eds., ''Writing the history of mathematics: its historical development'', Birkhäuser, 2002, p. 303. * {{DEFAULTSORT:Li, Rui 1768 births 1817 deaths Mathematicians from Jiangsu 18th-century Chinese mathematicians 19th-century Chinese mathematicians Historians of mathematics Scientists from Suzhou Qing dynasty people