Má Jiǔchóu 麻九疇 (zì Zhījī 知幾; 1183–1232) was a late-Jīn polymath, jìnshì 1226, scholar, mathematician, and physician. He and his circle preserved the Sānxiāo lùn (KR3eh047) of 劉完素 Liú Wánsù; the surviving textual witness was prepared from manuscripts obtained via Má from Liú’s descendants.