Python 线性代数 矩阵乘法

使用numpy就可以用矩阵了

虽然官方文档说了不要用这个类

原因:

Despite its convenience, the use of the numpy.matrix class is discouraged, since it adds nothing that cannot be accomplished with 2D numpy.ndarray objects, and may lead to a confusion of which class is being used.

不过不管了 先用着吧

以下实现了矩阵乘法运算

>>> import numpy as np
>>> A = np.mat('[1 2 3;4 5 6]')
>>> A
matrix([[1, 2, 3],
[4, 5, 6]])
>>> B = np.mat('2 0 -1;3 1 2]')
>>> B
matrix([[ 2,  0, -1],
[ 3,  1,  2]])
>>> 2*A - 3*B
matrix([[-4,  4,  9],
[-1,  7,  6]])