The Nine Chapters on the Mathematical Art, Vols. 1-3

Since the Northern Song dynasty, these techniques were rarely transmitted. Apart from the Mengxi Bitan Dream Pool Essays by Shen Kuo, few scholars paid attention to them, and the book nearly vanished. In the Qingyuan 1195–1200 period of the Southern Song, Bao Huanzhi finally obtained a copy from the family of Yang Zhongfu and had it copied into the imperial archives. However, it did not circulate widely, and by the Ming dynasty, it was lost again. For two or three hundred years, mathematicians have not been able to see the complete work. Only the portions recorded in the Yongle Dadian Great Canon of the Yongle Era remained, categorized and compiled, with all nine chapters present. Upon examination, the postscript after Bao Huanzhi states that the old diagrams transmitted since the Tang had been lost by the Song, and that the chapters on "Excess and Deficit" and "Equations" were missing the commentary by Chunfeng. Now, comparing what he said—