$\LaTeX$基本语法

行间与行内公式

使用两个\$以创建一个行内公式：$123$

使用两个\$\$以创建行间公式：$$f(x)$$

p.s:若想在markdown中写出\$而不发生转义，应当在每个\$符号前加\，比如\\$

（这个\的数量有点玄学，你自己看着加吧）

转义与形式变换

标准函数名

$\mathbb{R}^3\backslash{0}$

我服了，抄不动了，这转义符是真的多，自己看图吧(水印懒得去了)：

矩阵型

$\left(
    \begin{array}{cc}
        1 & 2 \\
        3 & 4
    \end{array}
\right)$

$\left( \begin{array}{cc} 1 & 2 \\ 3 & 4 \end{array} \right)$

$\left(
    \begin{array}{cc}
        1 & 2 \\
        3 & 4
    \end{array}
\right)
\left(
    \begin{array}{c}
        x \\
        y
    \end{array}
\right)$

$\left( \begin{array}{cc} 1 & 2 \\ 3 & 4 \end{array} \right) \left( \begin{array}{c} x \\ y \end{array} \right)$

$\left[
    \begin{array}{cc|c}
        1 & 2 & 3 \\
        4 & 5 & 6
    \end{array}
\right]$

$\left[ \begin{array}{cc|c} 1 & 2 & 3 \\ 4 & 5 & 6 \end{array} \right]$

$f(x)=\left\{
    \begin{array}{rcl} 
        1 & for & x>0 \\
        0 & for & x=0 \\
        -1 & for & x<0
    \end{array}
\right.$

$f(x)=\left\{\begin{array}{rcl} 1 & for & x>0 \\ 0 & for & x=0 \\ -1 & for & x<0 \end{array}\right.$

一个快速生成表格的网站：tablesgenerator

多行公式

%自带编号单行公式
$\begin{equation}
  a^2 + b^2 = c^2
\end{equation}$
$\begin{equation}
  a^2 + b^2 = c^2
\end{equation}$

$\begin{equation} a^2 + b^2 = c^2 \end{equation}$ $\begin{equation} a^2 + b^2 = c^2 \end{equation}$

%带对其点的多行公式，对其&
%\nonumber用于取消标号
\begin{align}
  a &= b + c \nonumber\\
  d &= e + f \nonumber
\end{align}

$$\begin{align} a &= b + c-4 \nonumber\\ max(d) &= e + f \nonumber \end{align}$$

%居中对齐的多行公式
\begin{gather}
  a = b + c \\
  d = e + f
\end{gather}

$\begin{gather} a = b + c \\ max(d) = e + f \end{gather}$

关于颜色

单公式全局颜色：\color{颜色控制码}

单公式局部颜色：\textcolor{颜色控制码}{文本}

$\colorbox{orange}{单公式无框盒子：}$ \colorbox{文字背景颜色码}{文本}

$\fcolorbox{red}{magenta}{单公式盒子:}$ \fcolorbox{边框颜色码}{文字背景颜色码}{文本}

颜色控制码自定义：\color{#F4E040}{文字}

$\color{#c0ffee}{\LaTeX}$

关于字体

字体大小

$\displaystyle \int f^{n}(x-x_a)~dx $
$\textstyle \int f^{n}(x-x_a)~dx $
$\scriptstyle \int f^{n}(x-x_a)~dx $
$\scriptscriptstyle \int f^{n}(x-x_a)~dx $

$\displaystyle \int f^{n}(x-x_a)~dx $

$\textstyle \int f^{n}(x-x_a)~dx $

$\scriptstyle \int f^{n}(x-x_a)~dx $

$\scriptscriptstyle \int f^{n}(x-x_a)~dx $

$\Huge A$ $\huge B$ $\LARGE C$ $\Large D$  $\large E$ $\pmb F$ $\normalsize F$ $\small G$ $\footnotesize H$ $\scriptsize I$ $\tiny J$

$\Huge A$ $\huge B$ $\LARGE C$ $\Large D$ $\large E$ $\pmb F$ $\normalsize F$ $\small G$ $\footnotesize H$ $\scriptsize I$ $\tiny J$

字体

$\mathbb{ABCDEFGHIJKLMNOPQRSTUVWXYZ}$ $\mathsf{ABCDEFGHIJKLMNOPQRSTUVWXYZ}$ $\mathtt{ABCDEFGHIJKLMNOPQRSTUVWXYZ}$ $\mathit{ABCDEFGHIJKLMNOPQRSTUVWXYZ}$ $\mathcal{ABCDEFGHIJKLMNOPQRSTUVWXYZ}$ $\mathrm{ABCDEFGHIJKLMNOPQRSTUVWXYZ}$ $\mathbf{ABCDEFGHIJKLMNOPQRSTUVWXYZ}$ $\mathop{ABCDEFGHIJKLMNOPQRSTUVWXYZ}$ $\mathscr{ABCDEFGHIJKLMNOPQRSTUVWXYZ}$ $\boldsymbol{ABCDEFGHIJKLMNOPQRSTUVWXYZ}$

附录

关于Markdown编辑LaTeX出现错误的解决

使用markdown编辑好blog再发布时，有时候会出现公式报错现象，比如

$\color{red}\rm Missing~or~unrecognized~delimiter~for ~\backslash left$

$\color{red}\rm Misplaced~\backslash hdashline$

$\color{red}\rm Misplaced~\backslash hline$

出现Missing or unrecognized delimiter for \left，Misplaced \hdashline和Misplaced \hline的原因一般是因为在markdown文件转html时用掉了LaTeX的\转义，导致实际在网页浏览LaTeX时，因为\的缺失出现公式报错。

解决方法非常简单，只需要在原LaTeX公式上的\处再加一个\即可，比如\\\。这样处理后就不用担心markdown转html时把\全转义完了。(如果原公式处是\\\，也应改为\\\\\\\)

一些规范

不能使用$sin(x)$
应当使用标准化的函数名$\sin(x)$

$sin(x)$

$\sin(x)$

英文字母只有在表示变量（或单一字符的函数名称）时才使用斜体，其余情况（如输入输出，常量）都应该使用罗马体（直立体）
$\rm ij$ \rm是范围变罗马体
$\text ij$ \text是单字符变罗马体
可使用$\text{ij}$扩展/限定范围

$x_i$，$i$表示变量$i=0,1,…$

$x_{\rm i}$，$\rm i$表示$\rm input$

一些例子

$\def\mathbi#1{\textbf{#1}}$
$\mathbi{A}$

$\def\mathbi#1{\textbf{#1}}$ $\mathbi{A}$

$\mathbb{R}^3\backslash\{0\}$

$\mathbb{R}^3\backslash{0}$

$f(x)=\frac 1 {\sqrt {2\pi} \sigma }{\rm e}^{-\frac {(x-\mu)}{2\sigma^2}}$

$f(x)=\frac 1 {\sqrt {2\pi} \sigma }{\rm e}^{-\frac {(x-\mu)}{2\sigma^2}}$

$$\sum_{n=1}^\infty \frac{1}{n^2} \to
      \textstyle \sum_{n=1}^\infty \frac{1}{n^2} \to
      \displaystyle \sum_{n=1}^\infty \frac{1}{n^2}$$

$$\sum_{n=1}^\infty \frac{1}{n^2} \to \textstyle \sum_{n=1}^\infty \frac{1}{n^2} \to \displaystyle \sum_{n=1}^\infty \frac{1}{n^2}$$

Compare $\displaystyle \lim_{t \to 0} \int_t^1 f(t)\, dt$
versus $\lim_{t \to 0} \int_t^1 f(t)\, dt$.

Compare $\displaystyle \lim_{t \to 0} \int_t^1 f(t), dt$ versus $\lim_{t \to 0} \int_t^1 f(t), dt$.

$\underset{j=1}{\overset{\infty}{\LARGE\mathrm K}}
\frac{a_j}{b_j}=
\cfrac{a_1}{
    b_1+\cfrac{a_2}{
        b_2+\cfrac{a_3}{
            b_3+\ddots}
        }
    }
$

$\underset{j=1}{\overset{\infty}{\LARGE\mathrm K}}\frac{a_j}{b_j}=\cfrac{a_1}{b_1+\cfrac{a_2}{b_2+\cfrac{a_3}{b_3+\ddots}}}$

$$
f\left(
   \left[ 
 \frac{
   1+\left\{x,y\right\}
 }{
   \left(
      \frac{x}{y}+\frac{y}{x}
   \right)
   \left(u+1\right)
 }+a
   \right]^{3/2}
\right)
$$

$$ f\left( \left[ \frac{ 1+\left\{x,y\right\} }{ \left( \frac{x}{y}+\frac{y}{x} \right) \left(u+1\right) }+a \right]^{3/2} \right) $$

$$
\begin{aligned}
a=&\left(1+2+3+  \cdots \right. \\
& \cdots+ \left. \infty-2+\infty-1+\infty\right)
\end{aligned}
$$

$$ \begin{aligned} a=&\left(1+2+3+ \cdots \right. \\ & \cdots+ \left. \infty-2+\infty-1+\infty\right) \end{aligned} $$

$ cost(\theta)=\begin{equation}
\left\{
    \begin{array}{lr}
        -log(h_\theta(x))&y =1 \\
        -log(1-h_\theta(x))&y=0
    \end{array}
\right.
\end{equation}$

$ cost(\theta)=\begin{equation} \left\{ \begin{array}{lr} -log(h_\theta(x))&y =1 \\ -log(1-h_\theta(x))&y=0 \end{array} \right. \end{equation}$

$$
\left\langle  
  q
\middle\|
  \frac{\frac{x}{y}}{\frac{u}{v}}
\middle| 
   p 
\right\rangle
$$

$$ \left\langle
q \middle| \frac{\frac{x}{y}}{\frac{u}{v}} \middle| p \right\rangle $$

$$\Bigg(\bigg(\Big(\big((x)\big)\Big)\bigg)\Bigg)$$

$$\Bigg(\bigg(\Big(\big((x)\big)\Big)\bigg)\Bigg)$$

$$\begin{array}{c|rrrr}
    & x^3 & x^2 & x^1 &  x^0\\
    & 1 & -6 & 11 & -6\\
    {\color{red}1} & \downarrow & 1 & -5 & 6\\
    \hline & 1 & -5 & 6 & |\phantom{-} {\color{blue}0}
\end{array}
$$

$$\begin{array}{c|rrrr}& x^3 & x^2 & x^1 & x^0\\ & 1 & -6 & 11 & -6\\ {\color{red}1} & \downarrow & 1 & -5 & 6\\ \hline & 1 & -5 & 6 & |\phantom{-} {\color{blue}0} \end{array} $$

$$\begin{array}{rrrr|ll}
     x^3 &           -6x^2 &  +11x &   -6 &      x-1 \\
    -x^3 &            +x^2 &       &      & x^2-5x+6 \\ \hline
         &           -5x^2 & +11x  &   -6            \\
         & \phantom{-}5x^2 & -5x   &      &       && \\ \hline
         &                 & +6x   &   -6            \\
         &                 & -6x   &   +6            \\ \hline
         &                 &  0    &    0
\end{array}$$

$$\begin{array}{rrrr|ll} x^3 & -6x^2 & +11x & -6 & x-1 \\ -x^3 & +x^2 & & & x^2-5x+6 \\ \hline & -5x^2 & +11x & -6 \\ & \phantom{-}5x^2 & -5x & & && \\ \hline & & +6x & -6 \\ & & -6x & +6 \\ \hline & & 0 & 0 \end{array}$$

$$\begin{array}{rrrrrrr|rr}
      & x_1 & x_2 & s_1 & s_2 & s_3 &  w &    & \text{ratio} \\ \hline
  s_1 &   0 &   1 &   1 &   0 &   0 &  0 &  8 &            - \\
    w & 1^* &  -1 &   0 &  -1 &   0 &  1 &  4 &            4 \\
  s_3 &   1 &   1 &   0 &   0 &   1 &  0 & 12 &           12 \\ \hdashline
      &   1 &  -1 &   0 &  -1 &   0 &  0 &  4 &              \\ \hline
  s_1 &   0 &   1 &   1 &   0 &   0 &  0 &  8 &              \\
  x_1 &   1 &  -1 &   0 &  -1 &   0 &  1 &  4 &              \\
  s_3 &   0 &   2 &   0 &   2 &   1 & -1 &  8 &              \\ \hdashline
      &   0 &   0 &   0 &   0 &   0 & -1 &  0 &
\end{array}$$

$$\begin{array}{rrrrrrr|rr} & x_1 & x_2 & s_1 & s_2 & s_3 & w & & \text{ratio} \\ \hline s_1 & 0 & 1 & 1 & 0 & 0 & 0 & 8 & - \\ w & 1^* & -1 & 0 & -1 & 0 & 1 & 4 & 4 \\ s_3 & 1 & 1 & 0 & 0 & 1 & 0 & 12 & 12 \\ \hdashline & 1 & -1 & 0 & -1 & 0 & 0 & 4 & \\ \hline s_1 & 0 & 1 & 1 & 0 & 0 & 0 & 8 & \\ x_1 & 1 & -1 & 0 & -1 & 0 & 1 & 4 & \\ s_3 & 0 & 2 & 0 & 2 & 1 & -1 & 8 & \\ \hdashline & 0 & 0 & 0 & 0 & 0 & -1 & 0 & \end{array}$$

$\begin{array}{|c|c|}\hline
自变量/因变量&          标量y           &             向量 y           &            矩阵Y               \\ \hline
标量x  & \frac{\partial y}{\partial x} & \frac{\partial y}{\partial x}&\frac{\partial Y}{\partial x}  \\ \hline
向量x  & \frac{\partial y}{\partial x} & \frac{\partial y}{\partial x}&\frac{\partial Y}{\partial x}  \\ \hline
矩阵X  & \frac{\partial y}{\partial X} & \frac{\partial y}{\partial X}&\frac{\partial Y}{\partial X}  \\ \hline
\end{array}$

$$\begin{array}{|c|c|}\hline 自变量/因变量 & 标量y& 向量 y&矩阵Y\\ \hline 标量x & \frac{\partial y}{\partial x} & \frac{\partial y}{\partial x}&\frac{\partial Y}{\partial x} \\ \hline 向量x & \frac{\partial y}{\partial x} & \frac{\partial y}{\partial x}&\frac{\partial Y}{\partial x} \\ \hline 矩阵X & \frac{\partial y}{\partial X} & \frac{\partial y}{\partial X}&\frac{\partial Y}{\partial X} \\ \hline \end{array}$$

更多例子请前往：mathjax-basic-tutorial-and-quick-reference查看