# Display math should end with $$

## Introduction

TeX engines have two ways of typesetting mathematics:

*inline math mode*where the mathematical content is contained within a paragraph, and*display math mode*where mathematical material is displayed separately, with additional space above or below it.

*Traditionally*, in the early days of TeX, mathematics intended to be typeset *inline*, typically within a paragraph, was surrounded by single `$`

characters: `$ inline math content...$`

and mathematics destined for *display* was surrounded by double `$`

characters: `$$ display math content...$$`

.

## Cause of the error `Display math should end with $$`

The error message `Display math should end with $$`

is generated by TeX engines when they try to finish typesetting some display math material but are unable to cleanly exit from display math mode due to incorrect TeX markup: as the error message indicates, the material to be typeset as display math has not been terminated with a second `$$`

pair.

### Examples: single error

This error is demonstrated in the following examples:

```
\documentclass{article}
\usepackage[textwidth=8cm]{geometry}
\begin{document}
\noindent \verb|$$ E=mc^2$| generates an error because the math is
started by \texttt{\$\$} but terminated by a single \texttt{\$}:
$$ E=mc^2$
\noindent\verb|$$ E=mc^2$ $| also generates an error because of the space between
the terminating \texttt{\$} characters:
$$ E=mc^2$ $
\end{document}
```

Open this **error-generating** example in Overleaf

This example produces the following output (image edited to highlight both errors):

### Example: two errors

**Note**: In some circumstances you may *also* see the related error Missing $ inserted, as the following example demonstrates by writing `$$E=mc^2`

, which omits both terminating `$`

characters:

```
\documentclass{article}
\usepackage[textwidth=8cm]{geometry}
\begin{document}
\noindent The following example omits both terminating \texttt{\$} characters, triggering the errors \texttt{Missing \$ inserted} and \texttt{Display math should end with \$\$.}
$$E=mc^2
\end{document}
```

Open this **error-generating** example in Overleaf

This example produces the following output:

## Solution

For the errors demonstrated above, the fix is straightforward—make sure you add the closing `$$`

at the end of your display math:

```
\documentclass{article}
\begin{document}
\noindent The solution is to ensure correct termination of the
display math by writing \verb|$$E=mc^2$$|:
$$E=mc^2$$
\end{document}
```

Open this **corrected** example in Overleaf

## Avoid using `$`

characters to typeset mathematics

Nowadays, standard (accepted) best practice is to *avoid* using explicit `$`

characters to typeset mathematics and use LaTeX *delimiters* instead, particularly for display math:

- for
**display math**: write`\[ display math content \]`

instead of`$$`

*display*math content...$$ - for
**inline math**: write`\( inline math content \)`

instead of`$`

*inline*math content...$

In reality, the LaTeX delimiters `\(`

, `\)`

, `\[`

and `\]`

are single-character *macros* which provide a sort of “insulating wrapper” around single and double `$`

characters. The LaTeX definitions of those delimiters (macros) do actually contain `$`

characters but with additional code that runs some tests/checks. They also generate LaTeX’s error message `Bad math environment delimiter`

. Using these delimiters (macros) has additional advantages because they can be redefined, perhaps temporarily, to achieve special effects.

## Overleaf guides

- Creating a document in Overleaf
- Uploading a project
- Copying a project
- Creating a project from a template
- Using the Overleaf project menu
- Including images in Overleaf
- Exporting your work from Overleaf
- Working offline in Overleaf
- Using Track Changes in Overleaf
- Using bibliographies in Overleaf
- Sharing your work with others
- Using the History feature
- Debugging Compilation timeout errors
- How-to guides
- Guide to Overleaf’s premium features

## LaTeX Basics

- Creating your first LaTeX document
- Choosing a LaTeX Compiler
- Paragraphs and new lines
- Bold, italics and underlining
- Lists
- Errors

## Mathematics

- Mathematical expressions
- Subscripts and superscripts
- Brackets and Parentheses
- Matrices
- Fractions and Binomials
- Aligning equations
- Operators
- Spacing in math mode
- Integrals, sums and limits
- Display style in math mode
- List of Greek letters and math symbols
- Mathematical fonts
- Using the Symbol Palette in Overleaf

## Figures and tables

- Inserting Images
- Tables
- Positioning Images and Tables
- Lists of Tables and Figures
- Drawing Diagrams Directly in LaTeX
- TikZ package

## References and Citations

- Bibliography management with bibtex
- Bibliography management with natbib
- Bibliography management with biblatex
- Bibtex bibliography styles
- Natbib bibliography styles
- Natbib citation styles
- Biblatex bibliography styles
- Biblatex citation styles

## Languages

- Multilingual typesetting on Overleaf using polyglossia and fontspec
- Multilingual typesetting on Overleaf using babel and fontspec
- International language support
- Quotations and quotation marks
- Arabic
- Chinese
- French
- German
- Greek
- Italian
- Japanese
- Korean
- Portuguese
- Russian
- Spanish

## Document structure

- Sections and chapters
- Table of contents
- Cross referencing sections, equations and floats
- Indices
- Glossaries
- Nomenclatures
- Management in a large project
- Multi-file LaTeX projects
- Hyperlinks

## Formatting

- Lengths in LaTeX
- Headers and footers
- Page numbering
- Paragraph formatting
- Line breaks and blank spaces
- Text alignment
- Page size and margins
- Single sided and double sided documents
- Multiple columns
- Counters
- Code listing
- Code Highlighting with minted
- Using colours in LaTeX
- Footnotes
- Margin notes

## Fonts

## Presentations

## Commands

## Field specific

- Theorems and proofs
- Chemistry formulae
- Feynman diagrams
- Molecular orbital diagrams
- Chess notation
- Knitting patterns
- CircuiTikz package
- Pgfplots package
- Typesetting exams in LaTeX
- Knitr
- Attribute Value Matrices

## Class files

- Understanding packages and class files
- List of packages and class files
- Writing your own package
- Writing your own class