線代 ⟩ 矩陣 ⟩ 行向量、列向量
矩陣的每一列稱為一個「列向量」: (⋮ai1ai2⋯aip⋮)\begin{pmatrix} & & \vdots & \\ \fcolorbox{black}{lightskyblue}{$a_{i1}$} & \fcolorbox{black}{lightskyblue}{$a_{i2}$} & \cdots & \fcolorbox{black}{lightskyblue}{$a_{ip}$} \\ & & \vdots & \end{pmatrix}ai1ai2⋮⋯⋮aip 我們用 Ai∗{\color{orange}\mathbf{A}_{i*}}Ai∗ 代表 [ai1ai2⋯aip]\begin{bmatrix} a_{i1} & a_{i2} & \cdots & a_{ip} \end{bmatrix}[ai1ai2⋯aip]
矩陣的每一行稱為一個「行向量」: (b1jb2j⋯⋮⋯bnj)\begin{pmatrix} & \fcolorbox{black}{yellowgreen}{$b_{1j}$} & \\ & \fcolorbox{black}{yellowgreen}{$b_{2j}$} & \\ \cdots & \vdots & \cdots \\ & \fcolorbox{black}{yellowgreen}{$b_{nj}$} & \end{pmatrix}⋯b1jb2j⋮bnj⋯ 我們用 B∗j{\color{orange}\mathbf{B}_{*j}}B∗j 代表 [b1jb2j⋮bpj]\begin{bmatrix} b_{1j} \\ b_{2j} \\ \vdots \\ b_{pj} \end{bmatrix} b1jb2j⋮bpj
矩陣乘法 ⟩ 行 ⨉ 列
內積
矩陣乘法
Mathematics for 3D Game Programming & Computer Graphics (2nd Edition, 2004)
(AB)ij=Ai∗B∗j(\mathbf{AB})_{{\color{blue}{i}}{\color{red}{j}}} = \mathbf{A}_{{\color{blue}{i}}*} \mathbf{B}_{*\color{red}{j}}(AB)ij=Ai∗B∗j
矩陣乘法 (定義)
(A∗kBk∗)ij=AikBkj( \mathbf{A}_{*\color{red}{k}} \mathbf{B}_{{\color{red}{k}}*} ) _{ij} = \mathbf{A}_{i \color{red}{k}} \mathbf{B}_{{\color{red}{k}} j} (A∗kBk∗)ij=AikBkj
矩陣乘法表格化 (引理)
AB=A∗1B1∗+A∗2B2∗+⋯+A∗pBp∗\mathbf{AB} = \mathbf{A}_{*\color{red}{1}} \mathbf{B}_{{\color{red}{1}}*} + \mathbf{A}_{*\color{red}{2}} \mathbf{B}_{{\color{red}{2}}*} + \cdots + \mathbf{A}_{*\color{red}{p}} \mathbf{B}_{{\color{red}{p}}*}AB=A∗1B1∗+A∗2B2∗+⋯+A∗pBp∗
矩陣乘法表格化 (定理)
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