matrix methods by many centuries. The preface of the book describes how Zhu traveled around China for 20 years as a teacher of mathematics. The methods of Jade Mirror of the Four Unknowns form the foundation for Wu's method of characteristic set. References Du, Shiran, "Zhu Shijie". Encyclopedia of China (Mathematics Edition), 1st ed. GRATTAN-GUINNESS, I.: The Norton History of the Mathematical Sciences, 1998. Guo Shuchun (tr. modern Chinese), Chen Zaixin (English tr.), Guo Jinhai (annotation), Zhu Shijie: Jade mirror of the Four Unknowns, Chinese and English bilingual, vol I & 2,Liaoning education Press, China, 2006. HO Peng-Yoke: Article on Chu Shih-chieh in the Dictionary of Scientific Biography, New York, 1970.hi Hoe, J.: The jade mirror of the four unknowns, Mingming Bookroom, New Zealand, 2007. Hoe, J.: Les systèmes d'équations polynômes dans le Siyuan Yujian (1303), Paris, Collège de France (Mémoires de l'Institut des Hautes Etudes Chinoises, Vol VI),1977. KONANTZ, E.L.:The Precious Mirror of the Four Elements, China journal of Science and Arts, Vol 2, No 4, 1924. LAM Lay-yong: Chu shih-chieh's Suan hsüeh ch'i-meng, Archive for the history of sciences, Vol 21, Berlin, 1970. MARTZLOFF, J-C.: A history of Chinese Mathematics, Springer-Verlag, Berlin, 1997. MIKAMI Yoshio, Development of Mathematics in China and Japan, Chapter 14 Chu Shih-chieh p89-98. 1913 Leipzig. Library of Congress catalog card number 61-13497. Mumford, David, "What’s so Baffling About Negative Numbers? — a Cross-Cultural Comparison", in C. S. Seshadri (Ed.), Studies in the History of Indian Mathematics, 2010. External links 1249 births 1314 deaths 13th-century Chinese mathematicians 14th-century Chinese mathematicians Educators from Hebei Medieval Chinese mathematicians Yuan dynasty science writers Writers from Hebei