# LaTeX Quick Reference

*Document structure, math, tables, figures, and more*

> Source: LaTeX Project (latex-project.org) · MIT

## Document Structure

### Minimal Document

```
\documentclass{article}
\begin{document}
Hello, LaTeX!
\end{document}
```

### Document Classes

| Command | Description |
|---------|-------------|
| `article` | Short documents, papers, reports |
| `report` | Longer documents with chapters |
| `book` | Full books with parts, chapters |
| `beamer` | Slide presentations |
| `letter` | Formal letters |

### Preamble

```
\documentclass[12pt, a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath, graphicx}
\title{My Document}
\author{Alice}
\date{\today}
```

### Sectioning

| Command | Description |
|---------|-------------|
| `\part{}` | Top-level division (book/report) |
| `\chapter{}` | Chapter (report/book only) |
| `\section{}` | Section |
| `\subsection{}` | Subsection |
| `\subsubsection{}` | Sub-subsection |
| `\paragraph{}` | Named paragraph |

## Text Formatting

### Font Styles

| Command | Description |
|---------|-------------|
| `\textbf{bold}` | **Bold** text |
| `\textit{italic}` | *Italic* text |
| `\underline{text}` | Underlined text |
| `\texttt{code}` | Monospace / typewriter |
| `\textsc{Small Caps}` | Small capitals |
| `\emph{emphasis}` | Emphasis (context-aware italic) |

### Font Sizes

| Command | Description |
|---------|-------------|
| `\tiny` | Smallest |
| `\small` | Smaller than normal |
| `\normalsize` | Default size |
| `\large / \Large` | Larger / even larger |
| `\huge / \Huge` | Huge / largest |

### Spacing & Breaks

| Command | Description |
|---------|-------------|
| `\\` | Line break |
| `\newpage` | Page break |
| `\vspace{1cm}` | Vertical space |
| `\hspace{1cm}` | Horizontal space |
| `\noindent` | Suppress paragraph indent |
| `~` | Non-breaking space |

## Math Mode

### Inline & Display Math

```
Inline: $E = mc^2$ or \( a^2 + b^2 = c^2 \)
Display: \[ \int_0^\infty e^{-x} dx = 1 \]
Numbered: \begin{equation}
  F = ma \label{eq:newton}
\end{equation}
```

### Common Symbols

| Command | Description |
|---------|-------------|
| `^ and _` | Superscript / subscript: `x^2`, `a_i` |
| `\frac{a}{b}` | Fraction: a/b |
| `\sqrt{x} / \sqrt[3]{x}` | Square / cube root |
| `\sum_{i=1}^{n}` | Summation |
| `\int_a^b` | Integral |
| `\lim_{x \to 0}` | Limit |
| `\infty` | Infinity symbol |

### Greek Letters

| Command | Description |
|---------|-------------|
| `\alpha \beta \gamma \delta` | Lowercase Greek |
| `\Gamma \Delta \Theta \Lambda` | Uppercase Greek |
| `\epsilon \sigma \omega \pi` | More lowercase Greek |
| `\mu \nu \rho \tau \phi` | Statistical / physics common |

### Matrices

```
\begin{bmatrix} 1 & 2 \\ 3 & 4 \end{bmatrix}
% pmatrix = (), vmatrix = ||, Bmatrix = {}
```

## Environments

### Common Environments

| Command | Description |
|---------|-------------|
| `document` | Main content area |
| `equation` | Numbered math equation |
| `align` | Aligned multi-line equations |
| `figure` | Floating figure |
| `table` | Floating table |
| `verbatim` | Literal text (no formatting) |
| `abstract` | Abstract block (article) |

### Aligned Equations

```
\begin{align}
  x &= a + b \\
  y &= c + d
\end{align}
% & marks alignment point, \\ breaks lines
```

## Lists & Tables

### Lists

```
\begin{itemize}
  \item Bullet point
  \item Another item
\end{itemize}
\begin{enumerate}
  \item First  \item Second
\end{enumerate}
```

### Tables

```
\begin{tabular}{|l|c|r|}
  \hline
  Name & Age & Score \\ \hline
  Alice & 25 & 88 \\
  Bob & 30 & 92 \\ \hline
\end{tabular}
```

### Column Specifiers

| Command | Description |
|---------|-------------|
| `l / c / r` | Left / center / right aligned |
| `\|` | Vertical line between columns |
| `p{3cm}` | Paragraph column (fixed width) |
| `\hline` | Horizontal line |
| `\cline{2-3}` | Partial horizontal line (cols 2-3) |

## Figures

### Including Images

```
\usepackage{graphicx}  % in preamble
\begin{figure}[htbp]
  \centering
  \includegraphics[width=0.8\textwidth]{img.png}
  \caption{A figure caption}
  \label{fig:example}
\end{figure}
```

### Placement Specifiers

| Command | Description |
|---------|-------------|
| `h` | Here (approximately) |
| `t` | Top of page |
| `b` | Bottom of page |
| `p` | Special float page |
| `!` | Override internal restrictions |
| `H` | Exactly here (requires `float`) |

### Cross-references

```
See Figure~\ref{fig:example} on
page~\pageref{fig:example}.
% Requires two compilations to resolve
```

## Bibliography

### BibTeX Workflow

```
% In .bib file:
@article{smith2025,
  author = {Smith, John},
  title = {A Great Paper},
  journal = {Nature}, year = {2025}
}
```

### Citing in Document

```
According to~\cite{smith2025} ...
\bibliographystyle{plain}
\bibliography{refs}  % refs.bib
```

### Bibliography Styles

| Command | Description |
|---------|-------------|
| `plain` | Numbered, sorted alphabetically |
| `unsrt` | Numbered, in citation order |
| `abbrv` | Like plain, abbreviated names |
| `apalike` | Author-year (APA-like) |

## Packages

### Essential Packages

| Command | Description |
|---------|-------------|
| `amsmath` | Advanced math environments |
| `graphicx` | Image inclusion |
| `hyperref` | Clickable links and references |
| `geometry` | Page margins: `\usepackage[margin=1in]{geometry}` |
| `booktabs` | Professional tables (`\toprule`, `\midrule`) |
| `xcolor` | Text and background colors |
| `listings` | Source code listings |
| `tikz` | Programmatic graphics and diagrams |
| `babel` | Multilingual support |
| `natbib` | Flexible citations (author-year, numeric) |

## Custom Commands

### New Commands

```
\newcommand{\R}{\mathbb{R}}    % shortcut
\newcommand{\norm}[1]{\|#1\|}  % 1 argument
Now use: $x \in \R$, $\norm{v}$
```

### Renewing & Environments

```
\renewcommand{\abstractname}{Summary}
\newenvironment{boxed}
  {\begin{center}\begin{tabular}{|p{0.9\textwidth}|}\hline}
  {\hline\end{tabular}\end{center}}
```

### Useful Shortcuts

```
\newcommand{\pd}[2]{\frac{\partial #1}{\partial #2}}
\newcommand{\dd}[2]{\frac{d #1}{d #2}}
% Usage: $\pd{f}{x}$, $\dd{y}{t}$
```

## Common Patterns

### Title Page

```
\begin{document}
\maketitle
\tableofcontents
\newpage
```

### Compilation

| Command | Description |
|---------|-------------|
| `pdflatex doc.tex` | Compile to PDF |
| `bibtex doc` | Process bibliography |
| `latexmk -pdf doc.tex` | Auto-compile (handles reruns) |
| `xelatex doc.tex` | Unicode/custom fonts support |

### Special Characters

| Command | Description |
|---------|-------------|
| `\% \$ \& \# \_` | Escaped reserved characters |
| `\textbackslash` | Backslash in text |
| `\{ \}` | Literal braces |
| ```text''` | Smart double quotes |
| `---` | Em dash |
| `--` | En dash |

### Useful Tips

| Command | Description |
|---------|-------------|
| `\label{} + \ref{}` | Cross-reference anything |
| `\input{file}` | Include another .tex file |
| `% comment` | Single-line comment |
| `\usepackage{lipsum}` | Dummy text: `\lipsum[1-3]` |