How does Feng Shui calculate the "three evil spirits"?

How does Feng Shui calculate the "three evil spirits"?

The positions of the three evil spirits can be calculated from the "three combined prescriptions": According to the three evil directions in the current year, Yin Wu Xu Sha is in the north, Shen Zi Chen is in the south, Si You Chou is in the east, Haimao Wei is in the west, that is It is said: If it is the year of the rat, dragon or monkey, then the three evil spirits will be in the south. In the year of horse, tiger and dog, the three evil spirits are in the north. If it is the year of rabbit, sheep or pig, then the three evil spirits are in the west. If it is the year of Rooster, Ox or Snake, then the three evil spirits will be in the east.