Numpy中的矩阵计算

矩阵初始化

支持matlab语句初始化,支持narray和array初始化。

>>> import numpy as np
>>> M = np.matrix("1 2 3;4 5 6;7 8 9")
>>> M
matrix([[1, 2, 3],
[4, 5, 6],
[7, 8, 9]])

矩阵相乘

支持点乘

>>> import numpy as np
>>> M = np.matrix("1 2 3;4 5 6;7 8 9")
>>> M
matrix([[1, 2, 3],
[4, 5, 6],
[7, 8, 9]])
>>> N = np.matrix(np.eye(3))
>>> N
matrix([[ 1., 0., 0.],
[ 0., 1., 0.],
[ 0., 0., 1.]])
>>> M*N
matrix([[ 1., 2., 3.],
[ 4., 5., 6.],
[ 7., 8., 9.]])

矩阵转置和逆

>>> M.T
matrix([[1, 4, 7],
[2, 5, 8],
[3, 6, 9]])
>>> M.I
matrix([[ -4.50359963e+15, 9.00719925e+15, -4.50359963e+15],
[ 9.00719925e+15, -1.80143985e+16, 9.00719925e+15],
[ -4.50359963e+15, 9.00719925e+15, -4.50359963e+15]])

矩阵的数组形式

>>> M.A
array([[1, 2, 3],
[4, 5, 6],
[7, 8, 9]])
>>> M.A1
array([1, 2, 3, 4, 5, 6, 7, 8, 9])
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