Chén Xū 陳訏
Style name Yányáng 言楊. Native of Hǎiníng 海寧 (Zhèjiāng). Born Shùnzhì 7 (1650); died Kāngxī 61 (1722). Provincial scholar (gòngshēng 貢生); served as Jiàoyù 教諭 (Educational Officer) of Chúnān 淳安 county.
A Kāngxī-period mathematical-pedagogical scholar. His sole Sìkù-preserved work is the Gōugǔ yǐnméng 句股引蒙 (KR3f0052) in 5 juàn, completed Kāngxī 61 (1722, rényín) — the year of his death.
The Sìkù 提要 of KR3f0052 is balanced: Chén Xū’s work has substantive technical errors (in the right-triangle analysis) but its pedagogical purpose — to introduce mathematics to beginners by combining various established methods (Western position-fixing, Méi Wéndǐng’s pen-arithmetic, Chéng Dàwèi’s Suànfǎ tǒngzōng multiplication-and-division, Méi Wéndǐng’s plane-trigonometry) — makes it useful as an introductory primer. The 提要’s verdict: “[although the work is technically deficient in certain respects], the calculation method’s refinement-and-subtlety cannot be obtained suddenly. This book proceeds from shallow to deep, opens the path step-by-step — for the beginning student is also not without merit. Looking at its name ‘Yǐnméng’ (Beginner’s Introduction), the purport is visible. Recording-and-preserving this exposition can also serve as the staging-post river-bridge for setting-out [in mathematical study]“.