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Wang Lai
Qing mathematician from She county whose Hengzhai Mathematics examined how many positive roots quadratic and cubic equations can have
In a calculation room, a wide table holds a board of black and yellow counting rods laid in neat bundles, beside an abacus, a ruler and a sheet with a circle divided into equal parts; one person sits at a far desk with their back turned, and terraced fields lie outside.
Also known as Zi Xiaoying · Hao Hengzhai
Wang Lai, courtesy name Xiaoying, styled Hengzhai, came from a poor family in She county, Anhui, and became a county student at fifteen. He later went to Beijing as a tribute student of special merit, qualified as a teacher in the Eight Banners schools, and worked on the astronomy and calendar treatises of the dynastic history, before taking a post as county instructor at Shidai, where he died in office in 1813. His main work, the seven-part Hengzhai Mathematics (Hengzhai suanxue), covers spherical trigonometry, equations, combinations and circle division, and its discussion of how many positive roots a quadratic or cubic equation may have, and how they relate to the coefficients, broke with the older practice of seeking a single root. He discussed mathematics with Jiao Xun and Li Rui, the three being known as the Three Friends Who Talk of Heaven, and the Draft History of Qing gives him a biography among the astronomers and mathematicians.
Life and times
Dates 1768 CE–1813 CE