How to write matrices in Latex ? matrix, pmatrix, bmatrix, vmatrix, Vmatrix. Here are few examples to write quickly matrices.

First of all, modify your preamble adding*

\usepackage{amsmath}

{*Thanks to Miss Paola Estrada for the fix.}

LateX pmatrix, bmatrix, vmatrix, Vmatrix

pmatrix, bmatrix, vmatrix, Vmatrix are Latex environments: -* p for parentheses -* b for brackets -* v for verts -* B for braces -* V for double verts.

How to write an m x n matrix in LaTeX

How to write an m x n matrix with big parentheses

\begin{equation*}
A_{m,n} = 
\begin{pmatrix}
a_{1,1} & a_{1,2} & \cdots & a_{1,n} \\
a_{2,1} & a_{2,2} & \cdots & a_{2,n} \\
\vdots  & \vdots  & \ddots & \vdots  \\
a_{m,1} & a_{m,2} & \cdots & a_{m,n} 
\end{pmatrix}
\end{equation*}
\[\begin{equation*} A_{m,n} = \begin{pmatrix} a_{1,1} & a_{1,2} & \cdots & a_{1,n} \\ a_{2,1} & a_{2,2} & \cdots & a_{2,n} \\ \vdots & \vdots & \ddots & \vdots \\ a_{m,1} & a_{m,2} & \cdots & a_{m,n} \end{pmatrix} \end{equation*}\]

Examples matrix 3 x 3 in LaTeX

With parentheses:

\begin{equation*}
A = 
\begin{pmatrix}
1 & 2 & 3 \\
4 & 5 & 6 \\
7 & 8 & 9
\end{pmatrix}
\end{equation*}
\[\begin{equation*} A = \begin{pmatrix} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{pmatrix} \end{equation*}\]

With brackets:

\begin{equation*}
B = 
\begin{bmatrix}
a & b & c \\
d & e & f \\
g & h & i
\end{bmatrix}
\end{equation*}
\[\begin{equation*} B = \begin{bmatrix} a & b & c \\ d & e & f \\ g & h & i \end{bmatrix} \end{equation*}\]

LateX matrix with no bracket

Without brackets:

\begin{equation}
   \begin{matrix} 
   a_{11} & a_{12} & a_{13}  \\
   a_{21} & a_{22} & a_{23}  \\
   a_{31} & a_{32} & a_{33}  \\
   \end{matrix} 
\end{equation}
\[\begin{equation} \begin{matrix} a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33} \\ \end{matrix} \end{equation}\]

LateX matrix determinant / vertical bar bracket

With vertical bar brackets:

\begin{equation}
   \begin{vmatrix} 
   a_{11} & a_{12} & a_{13}  \\
   a_{21} & a_{22} & a_{23}  \\
   a_{31} & a_{32} & a_{33}  \\
   \end{vmatrix} 
\end{equation}
\[\begin{equation} \begin{vmatrix} a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33} \\ \end{vmatrix} \end{equation}\]

Latex matrix with curly brackets

With curly brackets:

\begin{equation}
   \begin{Bmatrix} 
   a_{11} & a_{12} & a_{13}  \\
   a_{21} & a_{22} & a_{23}  \\
   a_{31} & a_{32} & a_{33}  \\
   \end{Bmatrix} 
\end{equation}
\[\begin{equation} \begin{Bmatrix} a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33} \\ \end{Bmatrix} \end{equation}\]

Latex matrix with double vertical bar brackets

With double vertical bar brackets:

\begin{equation}
   \begin{Vmatrix} 
   a_{11} & a_{12} & a_{13}  \\
   a_{21} & a_{22} & a_{23}  \\
   a_{31} & a_{32} & a_{33}  \\
   \end{Vmatrix} 
\end{equation}
\[\begin{equation} \begin{Vmatrix} a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33} \\ \end{Vmatrix} \end{equation}\]

Latex small inline matrix

Use smallmatrix environment

I love small matrice such $\big(\begin{smallmatrix} a & b\\ c & d \end{smallmatrix}\big)$

I love small matrice such $\big(\begin{smallmatrix} a & b\ c & d \end{smallmatrix}\big)$

Examples matrix 2 x 2 in LaTeX

Here are examples with matrix 2x2 with pmatrix, bmatrix, vmatrix, Vmatrix environments:

\begin{matrix} 
a & b \\
c & d 
\end{matrix}
\quad
\begin{pmatrix} 
a & b \\
c & d 
\end{pmatrix}
\quad
\begin{bmatrix} 
a & b \\
c & d 
\end{bmatrix}
\quad
\begin{vmatrix} 
a & b \\
c & d 
\end{vmatrix}
\quad
\begin{Vmatrix} 
a & b \\
c & d 
\end{Vmatrix}
\[\begin{matrix} a & b \\ c & d \end{matrix} \quad \begin{pmatrix} a & b \\ c & d \end{pmatrix} \quad \begin{bmatrix} a & b \\ c & d \end{bmatrix} \quad \begin{vmatrix} a & b \\ c & d \end{vmatrix} \quad \begin{Vmatrix} a & b \\ c & d \end{Vmatrix}\]