How to Write a Matrix in LaTeX
To write a matrix in LaTeX, load \usepackage{amsmath} and use a matrix environment inside math mode: pmatrix for round brackets, bmatrix for square brackets, vmatrix for determinant bars. Separate column entries with & and end each row with \\.
Example
\usepackage{amsmath}
\[
\begin{bmatrix}
1 & 2 & 3 \\
4 & 5 & 6
\end{bmatrix}
\quad
\begin{pmatrix} a \\ b \end{pmatrix}
\]Frequently asked questions
What is the difference between pmatrix and bmatrix?
pmatrix draws round parentheses ( ), bmatrix draws square brackets [ ], vmatrix draws single bars for a determinant, and Vmatrix draws double bars. All come from amsmath.
How do I add dots inside a matrix?
Use \cdots (horizontal), \vdots (vertical), and \ddots (diagonal): e.g. a_{11} & \cdots & a_{1n} on the top row and \ddots down the diagonal.
How do I control column alignment in a matrix?
Plain pmatrix/bmatrix centre entries. For custom alignment use the array environment inside \left( ... \right), or pmatrix* / bmatrix* from mathtools with an optional alignment argument.
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