# \diagonalmatrix

Used to generate a diagonal matrix from a comma-separated list of entries, typically inside \mqty{...} or related physics matrix macros.

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

## Metadata

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

## Syntax

### physics

Argument specification: `g`

Used to generate a diagonal matrix from a comma-separated list of entries, typically inside \mqty{...} or related physics matrix macros.

## Examples

```latex
\diagonalmatrix
```

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

```latex
\mqty{\diagonalmatrix{a,b}}
```

[Open in Playground](https://play.texform.dev/?input=%5Cmqty%7B%5Cdiagonalmatrix%7Ba%2Cb%7D%7D)

## Renderer support

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

## In TeXForm

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

### Expands to (physics)

```latex
\diagonalmatrix{#1,#2}
```

→

```latex
\mqty{#1} \\ & \mqty{#2}
```

Expands to a diagonal arrangement of \mqty-wrapped elements separated by & and \\.

### [physics/diagonalmatrix-to-dmat](https://texform.dev/rules/physics/diagonalmatrix-to-dmat)

Collapse diagonalmatrix to the shorter dmat helper.

Level: authoring. Fidelity: render.

```latex
\diagonalmatrix{#1}
```

→

```latex
\dmat{#1}
```

```latex
D=\mqty(\diagonalmatrix{\lambda_1,\lambda_2,\lambda_3})
```

→

```latex
D=\mqty(\dmat{\lambda_1,\lambda_2,\lambda_3})
```

## Equivalent forms

```latex
\dmat{...}
```

exact. Short alias provided by the physics package with identical parsing and behavior.

## See also

- [\\admat](https://texform.dev/latex/commands/admat)
- [\\antidiagonalmatrix](https://texform.dev/latex/commands/antidiagonalmatrix)
- [\\dmat](https://texform.dev/latex/commands/dmat)

## Test cases

### physics

| Input | Case | MathJax | KaTeX | XeTeX |
| --- | --- | --- | --- | --- |
| \diagonalmatrix | Positive: baseline | Pass | Fail | Pass |
| \diagonalmatrix{a} | Positive: vary:g[0] | Pass | Fail | Pass |