The so-called "quaternary" refers to a quaternary equation with four unknowns.
Zhu Shijie studied nine chapters of arithmetic all his life, and comprehensively inherited the mathematical achievements of Qin, Yang Hui and others. On the basis of one-dimensional, two-dimensional and three-dimensional equations at that time, he developed a four-dimensional equation, the representative work of which is "Meeting with Siyuan".
The encounter with Siyuan is regarded as another symbol of the peak of mathematics in China in Song and Yuan Dynasties, and an important milestone in the development of ancient mathematics in China.
"Meeting with Siyuan" mainly tells some mathematical problems such as "thinking skills", "superposition skills" and "calling skills". Meet Siyuan is divided into Volume I, Volume I, Volume II and Volume II.