# physics/norm-to-double-vert-fence

Rewrite norm to explicit double-vertical-bar fences.

https://texform.dev/rules/physics/norm-to-double-vert-fence

## Metadata

| Field | Value |
| --- | --- |
| Key | physics/norm-to-double-vert-fence |
| Level | faithful |
| Fidelity | render |
| Enabled by packages | physics |
| Profiles | Faithful, Corpus, Equiv |

## Rewrite patterns

### auto-sized

From:

```latex
\norm{#1}
```

To:

```latex
\left\| #1 \right\|
```

### fixed-size

From:

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

To:

```latex
\| #1 \|
```

## Examples

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

### norm

Before:

```latex
\norm{v}
```

After this rule:

```latex
\left\| v \right\|
```

Packages: base, physics.

Rendering verified with the declared packages.

### norm subscripted

Before:

```latex
\norm{A x-b}_2
```

After this rule:

```latex
\left\| A x-b \right\|_2
```

Packages: base, physics.

Rendering verified with the declared packages.

### norm star subscripted

Before:

```latex
\norm*{A x-b}_2
```

After this rule:

```latex
\| A x-b \|_2
```

Packages: base, physics.

Rendering verified with the declared packages.

## Triggers

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

## Eliminates

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

## Produces

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

## Same family

- [base/Big-class-variants-to-Big](https://texform.dev/rules/base/Big-class-variants-to-Big): Collapse \Bigl, \Bigr, \Bigm to \Big.
- [base/Bigg-class-variants-to-Bigg](https://texform.dev/rules/base/Bigg-class-variants-to-Bigg): Collapse \Biggl, \Biggr, \Biggm to \Bigg.
- [base/big-class-variants-to-big](https://texform.dev/rules/base/big-class-variants-to-big): Collapse \bigl, \bigr, \bigm to \big.
- [base/bigg-class-variants-to-bigg](https://texform.dev/rules/base/bigg-class-variants-to-bigg): Collapse \biggl, \biggr, \biggm to \bigg.
- [base/Big-delimiter-size-drop](https://texform.dev/rules/base/Big-delimiter-size-drop): Drop the fixed delimiter size imposed by \Big.
- [base/Bigg-delimiter-size-drop](https://texform.dev/rules/base/Bigg-delimiter-size-drop): Drop the fixed delimiter size imposed by \Bigg.
- [base/big-delimiter-size-drop](https://texform.dev/rules/base/big-delimiter-size-drop): Drop the fixed delimiter size imposed by \big.
- [base/bigg-delimiter-size-drop](https://texform.dev/rules/base/bigg-delimiter-size-drop): Drop the fixed delimiter size imposed by \bigg.
- [physics/absolutevalue-to-abs](https://texform.dev/rules/physics/absolutevalue-to-abs): Collapse absolutevalue to the shorter abs helper before fence expansion.
- [physics/evaluated-to-eval](https://texform.dev/rules/physics/evaluated-to-eval): Collapse evaluated to the shorter eval helper before eval expansion.
- [physics/quantity-to-qty](https://texform.dev/rules/physics/quantity-to-qty): Collapse quantity to the shorter qty helper.
- [physics/Bqty-to-brace-fence](https://texform.dev/rules/physics/Bqty-to-brace-fence): Rewrite Bqty to explicit brace fences.
- [physics/abs-to-vert-fence](https://texform.dev/rules/physics/abs-to-vert-fence): Rewrite abs to explicit vertical bar fences.
- [physics/bqty-to-bracket-fence](https://texform.dev/rules/physics/bqty-to-bracket-fence): Rewrite bqty to explicit bracket fences.
- [physics/pqty-to-paren-fence](https://texform.dev/rules/physics/pqty-to-paren-fence): Rewrite pqty to explicit parenthesis fences.
- [physics/eval-expand](https://texform.dev/rules/physics/eval-expand): Expand eval notation to the explicit fence-and-bar form.

## Notes

The star branch preserves fixed-size double bars instead of introducing left/right fences.

## Disable this rule

```python
TransformEngine(profile="corpus", disable_rules=["physics/norm-to-double-vert-fence"])
```

```javascript
new TransformEngine({ profile: 'corpus', disableRules: ['physics/norm-to-double-vert-fence'] })
```

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