from fractions import Fraction
import numpy as np
#设置矩阵元素输出用分数表示
np.set_printoptions(formatter={'all':lambda x: str(Fraction(x).limit_denominator())})

a = np.array([[0.8,-0.1,-0.2],[-0.5,0.5,-0.4],[-0.1,-0.3,0.8]])
print("分数形式显示原矩阵：")
print(a)

b = np.linalg.inv(a) #求逆矩阵
print("分数形式显示逆矩阵：")
print(b)