Summary of markdown/latex commonly used mathematical symbols

Braces

Automatic resize:
left & right

\left( \dfrac12 \left( \right) \right)

$$\left(\frac{1}{2}\left(\right)\right)$$

Fixed size:
big: $\left(\right[\{$
Big: $\left(\right[\{$
bigg: $\left(\right[\{$
Bigg: $\left(\right[\{$

Align

\begin{aligned}
A
& = B \\
& = C
\end{aligned}

$$\begin{array}{rl}A& =B\\ & =C\end{array}$$

matrix

\begin{matrix} 0 & 1 \\ 1 & 0 \end{matrix}
\quad
\begin{pmatrix} 0 & -i \\ i & 0 \end{pmatrix}
\quad
\begin{bmatrix} 0 & -1 \\ 1 & 0 \end{bmatrix}
\quad
\begin{Bmatrix} 1 & 0 \\ 0 & -1 \end{Bmatrix}
\quad
\begin{vmatrix} a & b \\ c & d \end{vmatrix}
\quad
\begin{Vmatrix} i & 0 \\ 0 & -i \end{Vmatrix}

$$\begin{array}{cc}0& 1\\ 1& 0\end{array}\left(\begin{array}{cc}0& -i\\ i& 0\end{array}\right)\left[\begin{array}{cc}0& -1\\ 1& 0\end{array}\right]\left\{\begin{array}{cc}1& 0\\ 0& -1\end{array}\right\}\left|\begin{array}{cc}a& b\\ c& d\end{array}\right|\Vert \begin{array}{cc}i& 0\\ 0& -i\end{array}\Vert$$

Long equal sign

A \xlongequal[sub]{super} B \\
A \xRightarrow[sup]{super} B \\
A \xLeftrightarrow[sup]{super} B \\

$$\begin{gathered} A\underset{sub}{\overset{super}{=}}B \\ A\underset{sup}{\overset{super}{\Rightarrow }}B \\ A\underset{sup}{\overset{super}{\iff }}B \end{gathered}$$

Forced conversion of subscripts and subscripts

limits:

\frac{1}{\sum\limits_{i=1}^n a_i}

$$\frac{1}{\sum _{i=1}^n{a}_i}$$