How to calculate yin and yang in the first set of geomantic omen,

This is more complicated. It depends on which Long Yuan Mountain Star is, the position of Mountain Star in the New Year's Day plate, and the corresponding Yin and Yang of Long Yuan in this position, so as to determine whether to fly forward or backward.

For example, at noon in Zi Shan, the constellation is 4, and the constellation is Tianyuan Dragon. On New Year's Day, the position of 4 is in the southeast. The three dragons in the position are: Chen Yunsi and Tianlongyuan are Xunzi. From the color on the compass, we can see the yin and yang of Xunzi. Red is yang and black is yin. You can also refer to the following table:

Due North (Kan): [Renzigui] (Heaven and Earth) (11) Northeast (Gen): [Ugly Gen Yin] (Heaven and Earth) (10) Due East (Earthquake): [Jiamao B] (Heaven and Earth) (11) Southeast (Xun): [Chen Xun]

In this way, we know that Xun is Yang, so the mountain star flies forward.

The judgment method of yin and yang of the first star is the same. In this case, the first star is 3, so you must fly backwards.

I hope it helps you.