LaTeX Packages Reference

% Input encoding (for older documents)
\usepackage[utf8]{inputenc}

% Font encoding
\usepackage[T1]{fontenc}

% Language support
\usepackage[english]{babel}
% or multiple languages
\usepackage[english,spanish,french]{babel}

% Better fonts
\usepackage{lmodern}

% Microtype (better typography)
\usepackage{microtype}

\usepackage{geometry}

% Common configurations
\geometry{margin=1in}
\geometry{left=1.5in, right=1in, top=1in, bottom=1in}
\geometry{a4paper, margin=2.5cm}
\geometry{letterpaper, landscape}

% Advanced options
\geometry{
  paperwidth=210mm,
  paperheight=297mm,
  left=25mm,
  right=25mm,
  top=30mm,
  bottom=30mm,
  headheight=15pt,
  headsep=10mm,
  footskip=15mm
}

\usepackage{fancyhdr}
\pagestyle{fancy}

% Clear defaults
\fancyhf{}

% Custom headers/footers
\fancyhead[L]{Left Header}
\fancyhead[C]{Center Header}
\fancyhead[R]{\thepage}
\fancyfoot[C]{Footer Text}

% Different odd/even pages
\fancyhead[LE,RO]{\thepage}
\fancyhead[LO,RE]{\leftmark}

% Custom styles
\fancypagestyle{plain}{
  \fancyhf{}
  \fancyfoot[C]{\thepage}
}

\usepackage{amsmath}

% Provides environments:
\begin{align}
  f(x) &= x^2 + 2x + 1 \\
  &= (x + 1)^2
\end{align}

\begin{gather}
  a = b + c \\
  d = e + f
\end{gather}

\begin{split}
  (a + b)^3 &= a^3 + 3a^2b \\
  &\quad + 3ab^2 + b^3
\end{split}

% Commands
\text{text in math}
\tfrac{a}{b}  % Text-style fraction
\dfrac{a}{b}  % Display-style fraction
\binom{n}{k}  % Binomial coefficient

\usepackage{amssymb}

% Provides symbols like:
\mathbb{R}    % Real numbers
\mathbb{Z}    % Integers
\mathbb{N}    % Natural numbers
\varnothing   % Empty set
\therefore    % Therefore
\because      % Because
\blacksquare  % QED symbol
\leqslant     % Less or equal (slanted)
\geqslant     % Greater or equal (slanted)

\usepackage{amsthm}

% Define theorem environments
\newtheorem{theorem}{Theorem}[section]
\newtheorem{lemma}[theorem]{Lemma}
\newtheorem{corollary}[theorem]{Corollary}

\theoremstyle{definition}
\newtheorem{definition}[theorem]{Definition}

\theoremstyle{remark}
\newtheorem{remark}[theorem]{Remark}

% Usage
\begin{theorem}[Fermat's Last Theorem]
No three positive integers $a$, $b$, and $c$ satisfy...
\end{theorem}

\begin{proof}
The proof is left as an exercise.
\end{proof}

\usepackage{mathtools}

% Additional features
\begin{align}
  f(x) &= \begin{cases}
    x^2 & \text{if } x > 0 \\
    0 & \text{otherwise}
  \end{cases}
\end{align}

% Better spacing
\coloneqq     % :=
\Coloneqq     % ::=
\eqqcolon     % =:

% Paired delimiters
\DeclarePairedDelimiter\abs{\lvert}{\rvert}
\DeclarePairedDelimiter\norm{\lVert}{\rVert}

% Usage
\abs{x}      % Absolute value
\abs*{x}     % Auto-sizing
\norm{v}     % Vector norm

\usepackage{graphicx}

% Include images
\includegraphics{image.png}
\includegraphics[width=5cm]{image.pdf}
\includegraphics[height=3cm]{image.jpg}
\includegraphics[scale=0.5]{image.eps}
\includegraphics[width=0.8\textwidth]{image.svg}

% Rotation and scaling
\includegraphics[angle=90]{image.png}
\rotatebox{45}{Rotated text}
\scalebox{2}{Scaled text}
\resizebox{5cm}{3cm}{Resized content}

% Figure environment
\begin{figure}[htbp]
  \centering
  \includegraphics[width=\textwidth]{plot.pdf}
  \caption{Important results}
  \label{fig:results}
\end{figure}

\usepackage{subcaption}

\begin{figure}
  \centering
  \begin{subfigure}{0.45\textwidth}
    \includegraphics[width=\textwidth]{image1.png}
    \caption{First subplot}
    \label{fig:sub1}
  \end{subfigure}
  \hfill
  \begin{subfigure}{0.45\textwidth}
    \includegraphics[width=\textwidth]{image2.png}
    \caption{Second subplot}
    \label{fig:sub2}
  \end{subfigure}
  \caption{Combined figure}
  \label{fig:combined}
\end{figure}

% Reference subfigures
See Figure~\ref{fig:sub1} and~\ref{fig:sub2}.

\usepackage{tikz}
\usetikzlibrary{arrows.meta, positioning, shapes}

% Simple drawing
\begin{tikzpicture}
  \draw (0,0) -- (2,1) -- (1,2) -- cycle;
  \node at (1,1) {Center};
\end{tikzpicture}

% Complex diagram
\begin{tikzpicture}[
  node distance=2cm,
  every node/.style={draw, circle}
]
  \node (A) {A};
  \node (B) [right=of A] {B};
  \node (C) [below=of A] {C};
  
  \draw[->] (A) -- (B);
  \draw[->] (A) -- (C);
  \draw[->] (B) -- (C);
\end{tikzpicture}

\usepackage{booktabs}

\begin{table}[htbp]
  \centering
  \caption{Professional table}
  \begin{tabular}{lcc}
    \toprule
    Item & Quantity & Price \\
    \midrule
    Apples & 5 & \$2.50 \\
    Oranges & 3 & \$1.80 \\
    Bananas & 6 & \$3.00 \\
    \midrule
    Total & 14 & \$7.30 \\
    \bottomrule
  \end{tabular}
\end{table}

\usepackage{array}

% New column types
\newcolumntype{C}{>{\centering\arraybackslash}X}
\newcolumntype{R}{>{\raggedleft\arraybackslash}X}

% Advanced tables
\begin{tabular}{>{\bfseries}l c r}
  \hline
  Bold Header & Center & Right \\
  \hline
  Row 1 & Data & Values \\
  Row 2 & More & Data \\
  \hline
\end{tabular}

\usepackage{longtable}

\begin{longtable}{lcc}
  \caption{Long table spanning pages} \\
  \toprule
  Column 1 & Column 2 & Column 3 \\
  \midrule
  \endfirsthead
  
  \multicolumn{3}{c}{{\tablename\ \thetable{} -- continued}} \\
  \toprule
  Column 1 & Column 2 & Column 3 \\
  \midrule
  \endhead
  
  \midrule
  \multicolumn{3}{r}{{Continued on next page}} \\
  \endfoot
  
  \bottomrule
  \endlastfoot
  
  % Table content
  Data & More & Values \\
  % ... many rows
\end{longtable}

\usepackage[style=authoryear,backend=biber]{biblatex}
\addbibresource{references.bib}

% Citation commands
\cite{key}              % (Author, Year)
\parencite{key}         % (Author, Year)
\textcite{key}          % Author (Year)
\citeauthor{key}        % Author
\citeyear{key}          % Year
\footcite{key}          % Footnote citation
\fullcite{key}          % Full citation

% Multiple citations
\parencite{key1,key2,key3}

% Bibliography
\printbibliography

\usepackage[authoryear,round]{natbib}

% Citation styles
\citet{key}     % Author (Year)
\citep{key}     % (Author, Year)
\citealt{key}   % Author Year
\citealp{key}   % Author, Year
\citeauthor{key}% Author
\citeyear{key}  % Year

% With page numbers
\citep[p.~25]{key}
\citep[see][p.~25]{key}

% Bibliography
\bibliographystyle{plainnat}
\bibliography{references}

\usepackage{enumitem}

% Customized itemize
\begin{itemize}[label=\textbullet, itemsep=0pt]
  \item First item
  \item Second item
\end{itemize}

% Customized enumerate
\begin{enumerate}[label=(\alph*), start=3]
  \item Third item (c)
  \item Fourth item (d)
\end{enumerate}

% Inline lists
\begin{enumerate*}[label=(\roman*)]
  \item One \item Two \item Three
\end{enumerate*}

% Description lists
\begin{description}[style=nextline]
  \item[Long term] Description on next line
  \item[Short] Inline description
\end{description}

\usepackage{listings}
\usepackage{xcolor}

% Configure style
\lstset{
  language=Python,
  basicstyle=\ttfamily\small,
  keywordstyle=\color{blue},
  commentstyle=\color{green},
  stringstyle=\color{red},
  numbers=left,
  numberstyle=\tiny,
  breaklines=true,
  frame=single
}

% Inline code
\lstinline{print("Hello")}

% Code block
\begin{lstlisting}[caption=Python example]
def fibonacci(n):
    if n <= 1:
        return n
    return fibonacci(n-1) + fibonacci(n-2)
\end{lstlisting}

% External file
\lstinputlisting[language=C]{code.c}

\usepackage{minted}

% Inline code
\mintinline{python}{print("Hello")}

% Code block
\begin{minted}[linenos,bgcolor=gray!10]{python}
def quicksort(arr):
    if len(arr) <= 1:
        return arr
    pivot = arr[len(arr) // 2]
    left = [x for x in arr if x < pivot]
    middle = [x for x in arr if x == pivot]
    right = [x for x in arr if x > pivot]
    return quicksort(left) + middle + quicksort(right)
\end{minted}

% External file
\inputminted{javascript}{script.js}

\usepackage{verbatim}

% Basic verbatim
\begin{verbatim}
Raw text with $special% characters&
\end{verbatim}

% Comment out sections
\begin{comment}
This entire section is commented out
and will not appear in the output.
\end{comment}

% Verbatim input from file
\verbatiminput{file.txt}

\usepackage{fontspec}

% Set main fonts
\setmainfont{Times New Roman}
\setsansfont{Arial}
\setmonofont{Courier New}

% Font features
\setmainfont[
  Ligatures=TeX,
  Numbers=OldStyle
]{Minion Pro}

% Custom font families
\newfontfamily\myfont{Comic Sans MS}
{\myfont This text uses Comic Sans}

\usepackage{microtype}

% Automatic improvements:
% - Character protrusion
% - Font expansion
% - Kerning adjustments
% - Tracking adjustments

% Manual adjustments
\textls[200]{Letter spaced text}
\microtypesetup{expansion=false}

\usepackage{hyperref}

% Configuration
\hypersetup{
  colorlinks=true,
  linkcolor=blue,
  filecolor=magenta,
  urlcolor=cyan,
  citecolor=green,
  pdfauthor={Author Name},
  pdftitle={Document Title},
  pdfsubject={Subject},
  pdfkeywords={keyword1, keyword2}
}

% Usage
\href{https://example.com}{Link text}
\url{https://example.com}
\nolinkurl{https://example.com}

% Internal links
\hyperref[label]{text}
\autoref{label}  % Automatic reference type

\usepackage{cleveref}

% Better references
\cref{eq:equation}     % Equation (1)
\Cref{fig:figure}      % Figure 1
\cref{sec:section}     % Section 2.1

% Multiple references
\cref{eq:1,eq:2,eq:3}  % Equations (1) to (3)
\cref{fig:a,fig:b}     % Figures 1 and 2

% Custom names
\crefname{algorithm}{algorithm}{algorithms}
\Crefname{algorithm}{Algorithm}{Algorithms}

\usepackage{siunitx}

% Numbers
\num{123456.789}        % 123,456.789
\num{1.23e-4}          % 1.23 × 10⁻⁴

% Units
\si{\meter\per\second}  % m/s
\si{\kilo\gram}        % kg
\si{\degree\celsius}    % °C

% Numbers with units
\SI{9.81}{\meter\per\second\squared}  % 9.81 m/s²
\SI{25}{\degree\celsius}              % 25 °C

% Ranges
\SIrange{10}{20}{\celsius}            % 10 °C to 20 °C
\numrange{1.2}{3.4}                   % 1.2 to 3.4

% Tables
\begin{tabular}{S[table-format=3.2]}
  \toprule
  {Values} \\
  \midrule
  1.23 \\
  45.67 \\
  890.12 \\
  \bottomrule
\end{tabular}

\usepackage[ruled,vlined]{algorithm2e}

\begin{algorithm}[H]
  \SetAlgoLined
  \KwData{Array $A$ of $n$ elements}
  \KwResult{Sorted array $A$}
  
  \For{$i \leftarrow 1$ \KwTo $n-1$}{
    $key \leftarrow A[i]$\;
    $j \leftarrow i-1$\;
    
    \While{$j \geq 0$ \KwAnd $A[j] > key$}{
      $A[j+1] \leftarrow A[j]$\;
      $j \leftarrow j-1$\;
    }
    $A[j+1] \leftarrow key$\;
  }
  
  \caption{Insertion Sort}
  \label{alg:insertion-sort}
\end{algorithm}

\usepackage{mhchem}

% Chemical formulas
\ce{H2O}              % Water
\ce{CaCl2}            % Calcium chloride
\ce{H2SO4}            % Sulfuric acid

% Chemical equations
\ce{2H2 + O2 -> 2H2O}
\ce{CaCO3 + 2HCl -> CaCl2 + H2O + CO2}

% Reaction arrows
\ce{A <=>> B}         % Equilibrium
\ce{A ->[catalyst] B} % Catalyst
\ce{A ->[\Delta] B}   % Heat

% States of matter
\ce{H2O(l)}           % Liquid
\ce{NaCl(s)}          % Solid
\ce{CO2(g)}           % Gas
\ce{Na+(aq)}          % Aqueous

\usepackage{multicol}

% Two-column text
\begin{multicols}{2}
  This text will be formatted in two columns.
  LaTeX automatically balances the columns.
\end{multicols}

% Three columns with separator
\begin{multicols}{3}[\section{Three Column Section}]
  Content in three columns with a section header.
\end{multicols}

% Column break
\begin{multicols}{2}
  First column content.
  \columnbreak
  Second column content.
\end{multicols}

\usepackage{setspace}

% Document-wide spacing
\singlespacing
\onehalfspacing
\doublespacing
\setstretch{1.5}

% Local spacing
\begin{spacing}{1.8}
  This paragraph has 1.8 line spacing.
\end{spacing}

\begin{singlespace}
  This paragraph is single-spaced.
\end{singlespace}

\begin{doublespace}
  This paragraph is double-spaced.
\end{doublespace}

\usepackage{parskip}

% Automatically sets:
% - \parindent to 0pt
% - \parskip to appropriate spacing
% - Adjusts list environments

% Manual control
\setlength{\parskip}{1em}
\setlength{\parindent}{0pt}

% Avoid these combinations:
% \usepackage{subfigure}  % Old package
% \usepackage{subcaption} % Use this instead

% \usepackage{cite}       % Basic citations
% \usepackage{natbib}     % Use this for advanced citations

% \usepackage{hyperref}
% \usepackage{cleveref}   % Load cleveref AFTER hyperref