# physics/physics-bra-expand

Expand bra to an explicit angle-bracket and bar fence form.

https://texform.dev/rules/physics/physics-bra-expand

## Metadata

| Field | Value |
| --- | --- |
| Key | physics/physics-bra-expand |
| Level | faithful |
| Fidelity | render |
| Enabled by packages | physics |
| Profiles | Faithful, Corpus, Equiv |

## Rewrite patterns

### bra-auto-sized

From:

```latex
\bra{#1}
```

To:

```latex
\left\langle #1 \right\vert
```

### bra-fixed-size

From:

```latex
\bra*{#1}
```

To:

```latex
\langle #1 \vert
```

## Examples

Examples show the rule in isolation, not a complete normalization profile.

### bra acting on operator

Before:

```latex
\bra{\psi} H
```

After this rule:

```latex
\left\langle \psi \right\vert H
```

Packages: base, physics.

Rendering verified with the declared packages.

### bra star fixed size

Before:

```latex
\bra*{\psi} H
```

After this rule:

```latex
\langle \psi \vert H
```

Packages: base, physics.

Rendering verified with the declared packages.

## Triggers

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

## Eliminates

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

## Produces

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

## Same family

- [physics/expectation-expand](https://texform.dev/rules/physics/expectation-expand): Expand expectation-value helpers to explicit angle brackets.
- [physics/matrixel-expand](https://texform.dev/rules/physics/matrixel-expand): Expand matrix elements to explicit angle-bracket and bar fences.
- [physics/physics-braket-expand](https://texform.dev/rules/physics/physics-braket-expand): Expand braket to an explicit angle-bracket form with a middle bar.
- [physics/physics-ket-expand](https://texform.dev/rules/physics/physics-ket-expand): Expand ket to an explicit bar and angle-bracket fence form.
- [physics/commutator-expand](https://texform.dev/rules/physics/commutator-expand): Expand commutators to explicit square-bracket fences.
- [physics/poisson-bracket-expand](https://texform.dev/rules/physics/poisson-bracket-expand): Expand poisson brackets to explicit brace fences.

## Notes

Covers the physics star branch, where star suppresses automatic fence sizing. The parser-level branch that merges an immediately following ket is outside this rule’s single-command rewrite.

## Disable this rule

```python
TransformEngine(profile="corpus", disable_rules=["physics/physics-bra-expand"])
```

```javascript
new TransformEngine({ profile: 'corpus', disableRules: ['physics/physics-bra-expand'] })
```

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