The record of three-point profit and loss method was first found in Guanzi Geography in the Spring and Autumn Period, which was related to the record of five tones of palace, sign, business, feather and angle.
By the time of Lu's Spring and Autumn Annals and Laws, it began to involve the length specification records of twelve laws, such as Huang Zhong and others. In ancient times, it was called "next life", and the upper five tones were found in the order of the three-point profit and loss law; Finding the law of the fourth degree was called "Shang Sheng" in ancient times. Starting from uniformity, having five children and six children, you can get twelve methods.
Extended data:
In the record, Guan Zhong actually made only five kinds of sounds: gong, Shang, Jiao, Zheng and Yu. After Guan Zhong, the "temperament chapter" of Lv Chunqiu continued to generate 1 1 times on the basis of Guan Zhong's five tones, that is, it was generated to "Huang Qingzhong", completing the generation of twelve laws.
However, after 1 1 times (that is, after the twelve laws), the "yellow bell" could not return to the original starting law, so that the twelve laws could not be repeated, and this problem was not solved. In the next two thousand years, a group of people of insight in China made unremitting explorations on this uniform issue. The "three-point profit and loss method" has different solutions in different periods, so it should be introduced in different periods.
Baidu encyclopedia-three-point profit and loss method