# \left

Used with \right to open automatically sized fences around a mathematical expression, including cases with an invisible delimiter such as \left.

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

## Metadata

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

## Syntax

### base

Argument specification: `m:D`

Used with \right to open automatically sized fences around a mathematical expression, including cases with an invisible delimiter such as \left.

## Examples

```latex
\left( x \right)
```

[Open in Playground](https://play.texform.dev/?input=%5Cleft%28+x+%5Cright%29)

```latex
\left. x \right|
```

[Open in Playground](https://play.texform.dev/?input=%5Cleft.+x+%5Cright%7C)

```latex
\left\langle x \right\rangle
```

[Open in Playground](https://play.texform.dev/?input=%5Cleft%5Clangle+x+%5Cright%5Crangle)

## 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

- [\\middle](https://texform.dev/latex/commands/middle)
- [\\right](https://texform.dev/latex/commands/right)

## Test cases

### base

| Input | Case | MathJax | KaTeX | XeTeX |
| --- | --- | --- | --- | --- |
| \left( a \right) | Positive: ctx:paired | Pass | Pass | Pass |
| \left[ a \right] | Positive: ctx:bracket | Pass | Pass | Pass |