# \eqalignno

Typesetting aligned equations with right-aligned equation numbers using Plain TeX syntax

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

## Metadata

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

## Syntax

### base

Argument specification: `m`

Typesetting aligned equations with right-aligned equation numbers using Plain TeX syntax

## Examples

```latex
\eqalignno{a & b & c \cr d & e & f}
```

[Open in Playground](https://play.texform.dev/?input=%5Ceqalignno%7Ba+%26+b+%26+c+%5Ccr+d+%26+e+%26+f%7D)

```latex
\eqalignno a
```

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

## Renderer support

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

## In TeXForm

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

### Discouraged in base

Plain TeX command that has been superseded by LaTeX environments.

```latex
\begin{align} $1 \end{align}
```

Standard LaTeX (amsmath) convention.

### [base/eqalignno-to-align-env](https://texform.dev/rules/base/eqalignno-to-align-env)

Rewrite eqalignno to the standard align* environment.

Level: authoring. Fidelity: reading.

```latex
\eqalignno{#1&#2&(#3)}
```

→

```latex
\begin{align*} #1&#2 \tag{#3} \end{align*}
```

```latex
\eqalignno{F(x)&=\int_0^x f(t)\,dt&(1)\cr F'(x)&=f(x)&(2)\cr F''(x)&=f'(x)&(3)}
```

→

```latex
\begin{align*} F(x)&=\int_0^x f(t)\,dt \tag{1}\\ F'(x)&=f(x) \tag{2}\\ F''(x)&=f'(x) \tag{3} \end{align*}
```

## See also

- [\\array](https://texform.dev/latex/commands/array)
- [\\cases](https://texform.dev/latex/commands/cases)
- [\\displaylines](https://texform.dev/latex/commands/displaylines)
- [\\eqalign](https://texform.dev/latex/commands/eqalign)
- [\\leqalignno](https://texform.dev/latex/commands/leqalignno)
- [\\matrix](https://texform.dev/latex/commands/matrix)
- [\\pmatrix](https://texform.dev/latex/commands/pmatrix)

## Test cases

### base

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