# \mathopen

Used to assign the open delimiter math class, like a left parenthesis.

https://texform.dev/latex/commands/mathopen

## Metadata

| Field | Value |
| --- | --- |
| Topic | [Delimiters](https://texform.dev/latex/topics/delimiters) |
| Packages | base |
| Allowed mode | math |
| Tags |  |
| Commonality | low |
| Kind | prefix |

## Syntax

### base

Argument specification: `m`

Used to assign the open delimiter math class, like a left parenthesis.

## Examples

```latex
\mathopen (
```

[Open in Playground](https://play.texform.dev/?input=%5Cmathopen+%28)

```latex
\mathopen{[}
```

[Open in Playground](https://play.texform.dev/?input=%5Cmathopen%7B%5B%7D)

## Renderer support

| Package | MathJax | KaTeX | XeTeX |
| --- | --- | --- | --- |
| base | full | full | full |

## In TeXForm

TeXForm parses this entry as prefix syntax; the package determines its argument specification.

## See also

- [\\mathbin](https://texform.dev/latex/commands/mathbin)
- [\\mathclose](https://texform.dev/latex/commands/mathclose)
- [\\mathinner](https://texform.dev/latex/commands/mathinner)
- [\\mathop](https://texform.dev/latex/commands/mathop)
- [\\mathord](https://texform.dev/latex/commands/mathord)
- [\\mathpunct](https://texform.dev/latex/commands/mathpunct)
- [\\mathrel](https://texform.dev/latex/commands/mathrel)

## Test cases

### base

| Input | Case | MathJax | KaTeX | XeTeX |
| --- | --- | --- | --- | --- |
| \mathopen{a} | Positive: baseline | Pass | Pass | Pass |
| \mathopen a | Positive: bare[0] | Pass | Pass | Pass |