《明史·志·卷九》
如太阳运行速度超过平均敷的时段，以八十八日九十一刻为一个象限，低于平均敷的时段，则以九十三日七十一刻为一个象限。现在只作九个象限，是举此作为例子。图中九行格子中的定差本敷，是被减数。
今止作九限者，举此为例也。其空格九行定差本数，为实也。
For example, when the solar motion exceeds the average coverage period, the time period of 88 days and 91 hours is taken as a quadrant, and when it is lower than the average coverage period, the time period of 93 days and 71 hours is taken as a quadrant. Now only nine quadrants are made, which is used as an example. The fixed difference in the nine rows of grids in the figure is the subtrahend.