# \\

A prefix command from base and textmacros, available in math and text mode. No description has been written yet.

https://texform.dev/latex/commands/-5c-

## Metadata

| Field | Value |
| --- | --- |
| Topic | [Spacing](https://texform.dev/latex/topics/spacing) |
| Packages | base, textmacros |
| Allowed mode | math, text |
| Tags | invisible, spacing |
| Commonality | — |
| Kind | prefix |

## Syntax

### base

Argument specification: `!s !o:L`

### textmacros

Argument specification: `!s !o:L`

## Common tasks

### How to break a line inside an aligned equation

\\ ends a row in align, cases, and matrix environments.

```latex
\begin{align} a &= b+c \\ &= d \end{align}
```

[Open in Playground](https://play.texform.dev/?input=%5Cbegin%7Balign%7D+a+%26%3D+b%2Bc+%5C%5C+%26%3D+d+%5Cend%7Balign%7D)

### How to add a line break in a stacked subscript

```latex
\sum_{\substack{1\le i\le n \\ i\neq j}} a_{ij}
```

[Open in Playground](https://play.texform.dev/?input=%5Csum_%7B%5Csubstack%7B1%5Cle+i%5Cle+n+%5C%5C+i%5Cneq+j%7D%7D+a_%7Bij%7D)

### How to break a long matrix row

```latex
\begin{pmatrix} a & b \\ c & d \end{pmatrix}
```

[Open in Playground](https://play.texform.dev/?input=%5Cbegin%7Bpmatrix%7D+a+%26+b+%5C%5C+c+%26+d+%5Cend%7Bpmatrix%7D)

## Package variants

| Package | Argument specification | Allowed mode | Description |
| --- | --- | --- | --- |
| base | !s !o:L | math | — |
| textmacros | !s !o:L | text | — |

## Renderer support

| Package | MathJax | KaTeX | XeTeX |
| --- | --- | --- | --- |
| base | full | full | full |
| textmacros | full | full | none |

## Usage frequency

24.30% of formulas in the measured corpus contain this entry, rank 2 of 263 entries with frequency data.

## In TeXForm

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

## Test cases

### base

| Input | Case | MathJax | KaTeX | XeTeX |
| --- | --- | --- | --- | --- |
| \\ | Positive: baseline | Pass | Pass | Pass |
| \\* | Positive: vary:s[0] | Pass | Pass | Pass |
| \\[1pt] | Positive: vary:o[1] | Pass | Pass | Pass |
| \\*[1pt] | Positive: maximal | Pass | Pass | Pass |
| \\[a] | Negative: neg:L[1] | Fail | Fail | Fail |

### textmacros

| Input | Case | MathJax | KaTeX | XeTeX |
| --- | --- | --- | --- | --- |
| \\ | Positive: baseline | Pass | Pass | Fail |
| \\* | Positive: vary:s[0] | Pass | Pass | Fail |
| \\[1pt] | Positive: vary:o[1] | Pass | Pass | Fail |
| \\*[1pt] | Positive: maximal | Pass | Pass | Fail |
| \\[a] | Negative: neg:L[1] | Pass | Fail | Fail |