gnomon. There were also a number of other geometrical problems and theoretical mathematical propositions posed by Yang that were strikingly similar to the Euclidean system. However, the first books of Euclid to be translated into Chinese was by the cooperative effort of the Italian Jesuit Matteo Ricci and the Ming official Xu Guangqi in the early 17th century. Yang's writing represents the first in which quadratic equations with negative coefficients of 'x' appear, although he attributes this to the earlier Liu Yi. Yang was also well known for his ability to manipulate decimal fractions. When he wished to multiply the figures in a rectangular field with a breadth of 24 paces 3 4⁄10 ft. and length of 36 paces 2 8⁄10, Yang expressed them in decimal parts of the pace, as 24.68 X 36.56 = 902.3008. See also History of mathematics List of mathematicians Chinese mathematics Notes References Needham, Joseph (1986). Science and Civilization in China: Volume 3, Mathematics and the Sciences of the Heavens and the Earth. Taipei: Caves Books, Ltd. Li, Jimin, "Yang Hui". Encyclopedia of China (Mathematics Edition), 1st ed. External links Yang Hui at MacTutor 1238 births 1298 deaths 13th-century Chinese mathematicians Magic squares Mathematicians from Zhejiang Medieval Chinese mathematicians Song dynasty science writers Writers from Hangzhou