Preface

Thanks to this blog, I learned to enble MathJax equation numbering in my blog.

However, when I tried to write down equations, it’s so confusing that whether I write down the things I want, and it always takes too much time for trial and error. So I decided to record the trials for future references.

LaTex Grammer

Basic

Inline style: use $...$ to define inline style latex equation

code $\sum_{i=0}^N\int_{a}^{b}g(t,i)\text{d}t$
show$\sum_{i=0}^N\int_{a}^{b}g(t,i)\text{d}t$

Display stype: use $$...$$ to define Display style

code$$\sum_{i=0}^N\int_{a}^{b}g(t,i)\text{d}t$$
show$$\sum_{i=0}^N\int_{a}^{b}g(t,i)\text{d}t$$

Greak letter

For all letter, check this post.

$\alpha$ => $\alpha$
$\beta$ => $\beta$
$\delta$ => $\delta$
$\theta$ => $\theta$
$\mu$ => $\mu$
$\pi$ => $\pi$
$\chi$ => $\chi$
$\epsilon$ => $\epsilon$

…

Capital:
$\Gamma$ => $\Gamma$
italic:
$\varGamma$ => $\varGamma$

Letter modifier

super/sub-script

superscript: ^
subscript: _
example: $C_n^2$ => $C_n^2$

Vector

$\vec a$ => $\vec a$
$\overrightarrow{xy}$ => $\overrightarrow{xy}$

Group

${}$
example: $10^{10}$ => $10^{10}$ ; $10^10$ => $10^10$

Bracket

$()$ => $()$
$[]$ => $[]$
$\\{\\} => $\{\}$

因为 Markdown 文件的处理实际上经过两个步骤，首先 Markdown 引擎把 Markdown 变为 html 文件, 然后 MathJax 再负责解释其中的数学公式。第一步中，由于 backslash 在 Markdown 属于特殊字符，用来转义，所以两个 backslash 经过 Markdown 引擎处理，只剩下一个，等到 MathJax 引擎处理时，实际上只有一个 backslash，MathJax 把它当作 LaTeX 中的空格>

$(\frac{x}{y})$ => $(\frac{x}{y})$
$\left(\frac{x}{y}\right)$ => $\left(\frac{x}{y}\right)$

sum/lim/integral/fraction/radical

$\sum_{i=1}^n{a_i}$ => $\sum_{i=1}^n{a_i}$
$\lim_{x\to 0}{(X+1)}$ => $\lim_{x\to 0}{(X+1)}$
$\int_0^\infty{fxdx}$ => $\int_0^\infty{fxdx}$
$\frac{formula1}{formula2}$ => $\frac{formula1}{formula2}$
$\sqrt[x]{y}$ => $\sqrt[x]{y}$

Function

$\function(x)$ => $\function(x)$
examples: $\sin x$ => $\sin x$, $\ln x$ => $ln x$, $\max(a,b,c)$ => $\max(a,b,c)$

Special symbol

code	show
$\infty$	$\infty$
$\cup$	$\cup$
$\cap$	$\cap$
$\subset$	$\subset$
$\subseteq$	$\subseteq$
$\supset$	$\supset$
$\in$	$\in$
$\notin$	$\notin$
$\varnothing$	$\varnothing$
$\forall$	$\forall$
$\exists$	$\exists$
$\lnot$	$\lnot$
$\nabla$	$\nabla$
$\partial$	$\partial$

Spaces

LaTex will ignore any spaces in the code
$a\ b$ => $a\ b$
$a\quad b => $a\quad b$

Other examples (or test cases):

$x<y$ => $x<y$
$x=y$ => $x=y$
$x\leq y$ => $x\leq y$
$x\neq y$ => $x\neq y$
$x\geq y$ => $x\geq y$

Equation number

Thanks to the post here.

Since I deploy this blog using Travis, it’s more easier for me to choose the first way … according to the post above.

According to MathJax official documentation, just paste the following script into the front of your Markdown file,

<script type="text/x-mathjax-config">
MathJax.Hub.Config({
  TeX: { equationNumbers: { autoNumber: "AMS" } }
});
</script>

1
2
3

$$\begin{equation}
e=mc^2
\end{equation}\label{eq1}$$

$\downarrow$ ( $\downarrow$ )

$$\begin{equation}
e=mc^2
\end{equation}\label{eq1}$$

$$\begin{equation}
\begin{aligned}
a &= b + c \\\\
  &= d + e + f + g \\\\
  &= h + i
\end{aligned}
\end{equation}\label{eq2}$$

$\downarrow$

$$\begin{equation}
\begin{aligned}
a &= b + c \\
&= d + e + f + g \\
&= h + i
\end{aligned}
\end{equation}\label{eq2}$$

reference equation

for the equations below:

$$\begin{align}
a &= b + c \label{eq3} \\\\
x &= yz \label{eq4}\\\\
l &= m - n \label{eq5}
\end{align}$$

$\downarrow$

$$\begin{align}
a &= b + c \label{eq3} \\
x &= yz \label{eq4}\\
l &= m - n \label{eq5}
\end{align}$$

You can use $\eqref{eq3}$ to refer to equation $\eqref{eq3}$, which is the same for $\eqref{eq4}$ and $\eqref{eq5}$.

font tests

$e$ => $e$
$\it{e}$ => $\it{e}$

to be continued: Matrix

References

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