#复习线性代数,矩阵相关python操作
>>> import numpy as np
>>> a=np.array([[1,2,3],[4,5,6],[7,8,9]])
>>> a
array([[1, 2, 3],
[4, 5, 6],
[7, 8, 9]])
>>> #a数组的转置直接使用.transpose()函数即可
>>> a.transpose()
array([[1, 4, 7],
[2, 5, 8],
[3, 6, 9]])
>>> #求数组的逆
>>> a
array([[ 3., 2., 3.],
[ 4., 7., 6.],
[ 7., 8., 11.]])
>>> np.linalg.inv(a)
array([[ 0.90625, 0.0625 , -0.28125],
[-0.0625 , 0.375 , -0.1875 ],
[-0.53125, -0.3125 , 0.40625]])
>>> #验证
>>> np.dot(a,np.linalg.inv(a))
array([[ 1.00000000e+00, -2.22044605e-16, 0.00000000e+00],
[ 4.44089210e-16, 1.00000000e+00, 0.00000000e+00],
[-8.88178420e-16, 0.00000000e+00, 1.00000000e+00]])
>>> #求数组的行列式值
>>> d
array([[1, 2],
[3, 4]])
>>> #d的逆
>>> f=np.linalg.inv(d)
>>> f
array([[-2. , 1. ],
[ 1.5, -0.5]])
>>> #d的行列式值
>>> np.linalg.det(d)
-2.0000000000000004
>>> np.linalg.det(f)
-0.49999999999999967