Mikowoo007的博客

行列式计算(按行展开)行标取标准排列列标取排列的所有可能，从不同列取出三个元素相乘，符号由列标排列奇偶性∣a11a12⋯a1na21a22⋯a2n⋮⋮⋱⋮an1an2⋯ann∣=∑j1j2⋯jn(−1)N(j1j2⋯jn)a1j1a2j2⋯anjn\begin{vmatrix}a_{11} & a_{12} & \cdots & a_{1n} \\a_{21} & a_{22} & \cdots & a_{2n} \\\vdots &amp

矩阵m×nm \times nm×n 矩阵[12345678]\begin{bmatrix}1 & 2 \\3 & 4 \\5 & 6 \\7 & 8 \end{bmatrix}⎣⎢⎢⎡​1357​2468​⎦⎥⎥⎤​import numpy as npA = np.array([[1,2],[3,4],[5,6],[7,8]])print(A)print(A.shape)[[1 2] [3 4] [5 6] [7 8]](4, 2)

向量行向量import numpy as npa = np.array([1,2,3,4])print(type(a))print(a)<class 'numpy.ndarray'>[1 2 3 4]列向量列向量 相当于一个 n×1n\times1n×1 的矩阵import numpy as npa = np.array([[1,2,3,4]])print(type(a))print(a)print(a.shape)print(type(a.T))print(