LaTex语法笔记
\( \boldsymbol{A} = \begin{bmatrix} a_{11} & a_{12}\\ a_{21} & a_{22} \end{bmatrix} \) 
\boldsymbol{A} = 
\begin{bmatrix}
    a_{11} & a_{12}\\
    a_{21} & a_{22} 
\end{bmatrix}

\( \begin{aligned} y & = (x+y)(x-y) \\ & = x^2-y^2 \end{aligned} \) 
\begin{aligned}
y
& = (x+y)(x-y) \\
& = x^2-y^2
\end{aligned}

\( \mathbb{R} \) 
\mathbb{R}

\( \infty \) 
\infty

\( \hat{a}, \check{a} \) 
\hat{a}, \check{a}

\( \mathscr{T}, \mathscr{P} \) 
\mathscr{T}, \mathscr{P}

\( \in \notin \subset \not\subset \supset \not\supset \cap \cup \) 
\in \notin \subset \not\subset \supset \note\supset \cap \cup

\( \left . \frac{\partial f} {\partial \boldsymbol{x}} \right \vert _{{\boldsymbol{x}}_0} \) 

\left . \frac{\partial f} {\partial \boldsymbol{x}} \right \vert  _{{\boldsymbol{x}}_0}