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])