# $\LaTeX$ Syntax

The following section describes how to add equations written using $\LaTeX$ to your documentation.

## Escaping Characters in Docstrings

Since some characters used in $\LaTeX$ syntax, such as `$`

and `\`

, are treated differently in docstrings. They need to be escaped using a `\`

character as in the following example:

```
"""
Here's some inline maths: ``\\sqrt[n]{1 + x + x^2 + \\ldots}``.
Here's an equation:
``\\frac{n!}{k!(n - k)!} = \\binom{n}{k}``
This is the binomial coefficient.
"""
func(x) = # ...
```

Note that for equations on the manual pages (in `.md`

files) the escaping is not necessary. So, when moving equations between the manual and docstrings, the escaping `\`

characters have to the appropriately added or removed.

To avoid needing to escape the special characters in docstrings the `raw""`

string macro can be used, combined with `@doc`

:

```
@doc raw"""
Here's some inline maths: ``\sqrt[n]{1 + x + x^2 + \ldots}``.
Here's an equation:
``\frac{n!}{k!(n - k)!} = \binom{n}{k}``
This is the binomial coefficient.
"""
func(x) = # ...
```

A related issue is how to add dollar signs to a docstring. They need to be double-escaped as follows:

```
"""
The cost was \\\$1.
"""
```

## Inline Equations

`Here's some inline maths: ``\sqrt[n]{1 + x + x^2 + \ldots}``.`

which will be displayed as

Here's some inline maths: $\sqrt[n]{1 + x + x^2 + \ldots}$.

## Display Equations

```
Here's an equation:
```math
\frac{n!}{k!(n - k)!} = \binom{n}{k}
```
This is the binomial coefficient.
---
To write a system of equations, use the `aligned` environment:
```math
\begin{aligned}
\nabla\cdot\mathbf{E} &= 4 \pi \rho \\
\nabla\cdot\mathbf{B} &= 0 \\
\nabla\times\mathbf{E} &= - \frac{1}{c} \frac{\partial\mathbf{B}}{\partial t} \\
\nabla\times\mathbf{B} &= - \frac{1}{c} \left(4 \pi \mathbf{J} + \frac{\partial\mathbf{E}}{\partial t} \right)
\end{aligned}
```
These are Maxwell's equations.
```

which will be displayed as

Here's an equation:

\[\frac{n!}{k!(n - k)!} = \binom{n}{k}\]

This is the binomial coefficient.

To write a system of equations, use the `aligned`

environment:

\[\begin{aligned} \nabla\cdot\mathbf{E} &= 4 \pi \rho \\ \nabla\cdot\mathbf{B} &= 0 \\ \nabla\times\mathbf{E} &= - \frac{1}{c} \frac{\partial\mathbf{B}}{\partial t} \\ \nabla\times\mathbf{B} &= - \frac{1}{c} \left(4 \pi \mathbf{J} + \frac{\partial\mathbf{E}}{\partial t} \right) \end{aligned}\]

These are Maxwell's equations.