---
title: Math
description: Compile TeX to MathML at build time, with nothing shipped to the browser.
---

Math is off by default. Turn it on and dollar-delimited TeX compiles to MathML during the build:

```rust filename="build.rs"
use proa_docs_build::{Config, MathMode};

let config = Config::new().source(source.markdown(pipeline.math(MathMode::MathMl)));
```

```mdx filename="content/performance.mdx"
Render cost is $O(n)$ in the number of dynamic slots, not in template size.
```

## Why MathML rather than KaTeX

The generated markup renders natively in every modern browser. **No client JavaScript, no stylesheet, no font.**

That is the difference between this and the usual approach. A docs site with KaTeX ships a renderer and a font file to every reader on every page; a Proa docs page with math ships bytes that were already going to be there. It is the same argument as build-time syntax highlighting, applied to equations.

| Mode | Behaviour |
|---|---|
| `MathMode::Disabled` *(default)* | `$…$` passes through as literal text |
| `MathMode::MathMl` | TeX compiles to MathML during the build |

Leaving it disabled is correct for most sites — prose that never uses math should not pay for a TeX parser in the build.

## Related

[Code block](/docs/proa-docs/code-block) · [Mermaid](/docs/proa-docs/mermaid) · [Configuration](/docs/proa-docs/configuration)