Customizing Theorem, Figure, And Table Numbering In Latex

Defining Your Own Counters

LaTeX provides several built-in counters for numbering elements like equations, figures, and tables. However, you may want to define your own counter variables to create custom numbering schemes.

How to Create New Counters

Use the \newcounter command to define a new counter, specifying the name of the counter. For example:


This creates a new counter called "theorem" that can be used to number theorem-like environments.

Incrementing and Resetting Counters

The \stepcounter command increments a counter variable by 1. To increment the "theorem" counter use:


You can reset a counter to 0 or any other number with the \setcounter command:


Setting Counter Values

To manually set a counter value, pass the desired number as an argument to \setcounter. For example, to set the theorem counter to 5:


This will override the current value of the counter.

Numbering Equations

LaTeX provides built-in support for numbering equations. Here are some ways to customize equation numbering.

Using the Equation Counter

The equation counter is automatically incremented each time you enter a math environment like \[ ... \] or \begin{equation}. To number an equation, use the \label and \ref commands:

Equation \ref{eq:Einstein} states $E=mc^2$.

Changing Equation Number Formats

To change the way equation numbers are formatted, redefine \theequation. For example:


Will format equation numbers as simple numerals like "1", "2", "3" instead of with parentheses.

Restarting Equation Numbers by Section

To restart equation numbering at 1 in each new section, use:


Put this in the preamble before \begin{document}.

Customizing Theorem Environments

LaTeX's built-in theorem-like environments such as \begin{theorem} are numbered sequentially. Here's how to customize them.

Modifying the Theorem Style

To change the way theorems are formatted, redefine the \newtheoremstyle command. For example, to produce bold theorem headings, use:

  {\bfseries}{.}{5pt plus 1pt minus 1pt}
  {\thmname{#1}\thmnumber{ #2}\thmnote{ {\bf (#3)}}}

Defining New Theorem-like Environments

Use \newtheorem to create additional theorem-like environments sharing the same counter:


This defines a "proposition" environment numbered like theorems.

Setting Separate Theorem Number Sequences

To number different theorem types independently, define a new counter for each one:


Now propositions and theorems will have separate numbering.

Formatting Tables and Figures

The presentation of tables and figures can be customized as well.

Changing the Numbering Style

Redefine \thefigure and \thetable to change the figure and table numbering format:


This will number figures with Roman numerals and tables with Arabic numerals.

Setting the Number Format

Use #1, #2 etc. within \thefigure or \thetable to insert padding:


Figures will be numbered as 1.1, 1.2, etc.

Adding Prefixes to Labels

You can append prefixes like "Fig" to figure numbers:


Figures will then be labeled Fig1, Fig2, and so on.

Restarting Numbering by Section

To restart figure and table numbering in each section, use:


Troubleshooting Numbering Issues

Sometimes figure, table, equation or theorem numbers may act unpredictably. Here is how to fix some common issues.

Dealing with Missing Numbers

If cross-references show missing numbers like "Figure ??", it usually means the figure or label was changed after the reference was written. Compile the document twice to refresh the references.

Understanding LaTeX’s Counters

Counters hold values that increase or reset automatically in LaTeX. If a custom counter behaves strangely, check if the underlying LaTeX counters were modified.

Resetting and Clearing Counters

To start a counter over from 1, \setcounter can be used:


To clear a counter value completely, use:


Additional Numbering Customizations

Here are a few other ways LaTeX allows customizing numbering behavior.

Numbering Lines in Documents

The lineno and nolineno packages can add line numbers alongside text paragraphs for referencing.

Adding Line Numbers to Equations

The equaton and leqno packages can number individual lines within multiline equations.

Custom List Numbering Formats

Enumerated lists can be customized to use letters, roman numerals, etc. with packages like enumerate.

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