Markedown常用数学公式

本文已参与「新人创作礼」活动，一起开启掘金创作之路。

Markdown中数学符号

符号	代码	符号	代码
$\sum_{i=0}^n$	$\sum_{i=0}^n$	$\circ$	$\circ$
$\leq$	$\leq$	$\geq$	$ \geq $
$\prod$	$\prod$	$\approx$	$\approx$
$\neq$	$\neq$	$\iint$	$\iint$
$\int$	$\int$	$\nabla$	$\nabla$
$\oint$	$\oint$	$\because$	$\because$
$\infty$	$\infty$	$\therefore$	$\therefore$
$\exists$	$\exists$	$\forall$	$\forall$
$\emptyset$	$\emptyset$	$\bigcup$	$\bigcup$
$\in$	$\in$	$\bigcap$	$\bigcap$
$\notin$	$\notin$	$\subset$	$\subset$
$\subseteq$	$\subseteq$	$\bigvee$	$\bigvee$
$\hat{y}$	$\hat{y}$	$\Rightarrow$	$\Rightarrow$
$\lim_{a\to \infty}$	\lim_{a\to \infty}	$\mathrm{d} x$	\mathrm{d} x

常用希腊字母

大写	markdown	小写	markdown
A	A	α	\alpha
B	B	β	\beta
Γ	\Gamma	γ	\gamma
Δ	\Delta	δ	\delta
E	E	ϵ	\epsilon
ε	\varepsilon	$\psi$	\psi
Z	Z	ζ	\zeta
H	H	η	\eta
Θ	\Theta	θ	\theta
I	I	ι	\iota
K	K	κ	\kappa
Λ	\Lambda	λ	\lambda
M	M	μ	\mu
N	N	ν	\nu
$\Xi$	\Xi	ξ	\xi
O	O	ο	\omicron
Π	\Pi	π	\pi
P	P	ρ	\rho
Σ	\Sigma	σ	\sigma

常见数学公式

• 分段函数

$$
f(x) = \left\{
  \begin{array}{lr}
    x^2 &  x < 0\\
    x^3 &  x \ge 0
  \end{array}
\right.
$$

$$
u(x) = 
  \begin{cases} 
   \exp{x} & \text{if } x \geq 0 \\
   1       & \text{if } x < 0
  \end{cases}
$$
858

• 方程组

  $$
  \left\{ 
  \begin{array}{c}
      a_1x+b_1y+c_1z=d_1 \\ 
      a_2x+b_2y+c_2z=d_2 \\ 
      a_3x+b_3y+c_3z=d_3
  \end{array}
  \right. 
  $$
  

  $$\left\{ \begin{array}{c} a_1x+b_1y+c_1z=d_1 \\ a_2x+b_2y+c_2z=d_2 \\ a_3x+b_3y+c_3z=d_3 \end{array} \right.$$

• 推导过程

  $$
  \begin{aligned}
  \frac{\partial J(\theta)}{\partial\theta_j}
  & = -\frac1m\sum_{i=0}^m(y^i-h_\theta(x^i)) \frac{\partial}{\partial\theta_j}(y^i-h_\theta(x^i)) \\
  & = -\frac1m\sum_{i=0}^m(y^i-h_\theta(x^i)) \frac{\partial}{\partial\theta_j}(\sum_{j=0}^n\theta_jx_j^i-y^i) \\
  & = -\frac1m\sum_{i=0}^m(y^i-h_\theta(x^i))x^i_j
  \end{aligned}
  $$
  
  

  $$\begin{aligned} \frac{\partial J(\theta)}{\partial\theta_j} & = -\frac1m\sum_{i=0}^m(y^i-h_\theta(x^i)) \frac{\partial}{\partial\theta_j}(y^i-h_\theta(x^i)) \\ & = -\frac1m\sum_{i=0}^m(y^i-h_\theta(x^i)) \frac{\partial}{\partial\theta_j}(\sum_{j=0}^n\theta_jx_j^i-y^i) \\ & = -\frac1m\sum_{i=0}^m(y^i-h_\theta(x^i))x^i_j \end{aligned}$$

• 特殊括号以及上下标

  $$
  \tbinom{n}{k} \\
  \binom{n}{k}  \\
  {n\brack k}\\
   {n\choose k} \\
   {n\brace k}\\
   \overset{x}{y}\\
  $$
  

• 加粗：$\pmb{字母}$ 加粗倾斜：$\boldsymbol{字母}$