# TeX Input Processor Options

The options below control the operation of the TeX input
processor that is run when you include `'input/tex'`

,
`'input/tex-full'`

, or `'input/tex-base'`

in the `load`

array of
the `loader`

block of your MathJax configuration, or if you load a
combined component that includes the TeX input jax. They are listed
with their default values. To set any of these options, include a
`tex`

section in your `MathJax`

global object.

## The Configuration Block

```
MathJax = {
tex: {
packages: ['base'], // extensions to use
inlineMath: [ // start/end delimiter pairs for in-line math
['\\(', '\\)']
],
displayMath: [ // start/end delimiter pairs for display math
['$$', '$$'],
['\\[', '\\]']
],
processEscapes: true, // use \$ to produce a literal dollar sign
processEnvironments: true, // process \begin{xxx}...\end{xxx} outside math mode
processRefs: true, // process \ref{...} outside of math mode
digits: /^(?:[0-9]+(?:\{,\}[0-9]{3})*(?:\.[0-9]*)?|\.[0-9]+)/,
// pattern for recognizing numbers
tags: 'none', // or 'ams' or 'all'
tagSide: 'right', // side for \tag macros
tagIndent: '0.8em', // amount to indent tags
useLabelIds: true, // use label name rather than tag for ids
maxMacros: 10000, // maximum number of macro substitutions per expression
maxBuffer: 5 * 1024, // maximum size for the internal TeX string (5K)
baseURL: // URL for use with links to tags (when there is a <base> tag in effect)
(document.getElementsByTagName('base').length === 0) ?
'' : String(document.location).replace(/#.*$/, '')),
formatError: // function called when TeX syntax errors occur
(jax, err) => jax.formatError(err)
}
};
```

Note that some extensions make additional options available. See the TeX Extension Options section below for details.

Note

The default for `processEscapes`

has changed from
`false`

in version 2 to `true`

in version 3.

Note

Prior to version 3.2, the `multlineWidth`

option used to be in the
main `tex`

block, but it is now in the `ams`

sub-block of the
`tex`

block. Version 3.2 includes code to move the configuration
from its old location to its new one, but that
backward-compatibility code will be removed in a future version.

## Option Descriptions

- packages: ['base']
This array lists the names of the packages that should be initialized by the TeX input processor. The input/tex and input/tex-full components automatically add to this list the packages that they load. If you explicitly load addition tex extensions, you should add them to this list. For example:

MathJax = { loader: {load: ['[tex]/enclose']}, tex: { packages: {'[+]': ['enclose']} } };

This loads the enclose extension and activates it by including it in the package list.

You can remove packages from the default list using

`'[-]'`

rather than`[+]`

, as in the followiong example:MathJax = { tex: { packages: {'[-]': ['noundefined']} } };

This would disable the noundefined extension, so that unknown macro names would cause error messages rather than be displayed in red.

If you need to both remove some default packages and add new ones, you can do so by including both within the braces:

MathJax = { loader: {load: ['[tex]/enclose']}, tex: { packages: {'[-]': ['noundefined', 'autoload'], '[+]': ['enclose']} } };

This disables the noundefined and autoload extensions, and adds in the enclose extension.

- inlineMath: [['\\\(','\\\)']]
This is an array of pairs of strings that are to be used as in-line math delimiters. The first in each pair is the initial delimiter and the second is the terminal delimiter. You can have as many pairs as you want. For example,

inlineMath: [ ['$','$'], ['\\(','\\)'] ]

would cause MathJax to look for

`$...$`

and`\(...\)`

as delimiters for in-line mathematics. (Note that the single dollar signs are not enabled by default because they are used too frequently in normal text, so if you want to use them for math delimiters, you must specify them explicitly.)Note that the delimiters can’t look like HTML tags (i.e., can’t include the less-than sign), as these would be turned into tags by the browser before MathJax has the chance to run. You can only include text, not tags, as your math delimiters.

- displayMath: [ ['$$','$$'], ['\\\[','\\\]'] ]
This is an array of pairs of strings that are to be used as delimiters for displayed equations. The first in each pair is the initial delimiter and the second is the terminal delimiter. You can have as many pairs as you want.

Note that the delimiters can’t look like HTML tags (i.e., can’t include the less-than sign), as these would be turned into tags by the browser before MathJax has the chance to run. You can only include text, not tags, as your math delimiters.

- processEscapes: false
When set to

`true`

, you may use`\$`

to represent a literal dollar sign, rather than using it as a math delimiter, and`\\`

to represent a literal backslash (so that you can use`\\\$`

to get a literal`\$`

or`\\$...$`

to get a backslash just before in-line math). When`false`

,`\$`

will not be altered, and its dollar sign may be considered part of a math delimiter. Typically this is set to`true`

if you enable the`$ ... $`

in-line delimiters, so you can type`\$`

and MathJax will convert it to a regular dollar sign in the rendered document.

- processRefs: true
When set to

`true`

, MathJax will process`\ref{...}`

outside of math mode.

- processEnvironments: true
When

`true`

, tex2jax looks not only for the in-line and display math delimiters, but also for LaTeX environments (`\begin{something}...\end{something}`

) and marks them for processing by MathJax. When`false`

, LaTeX environments will not be processed outside of math mode.

- digits: /^(?:[0-9]+(?:\{,\}[0-9]{3})*(?:\.[0-9]*)?|\.[0-9]+)/
This gives a regular expression that is used to identify numbers during the parsing of your TeX expressions. By default, the decimal point is

`.`

and you can use`{,}`

between every three digits before that. If you want to use`{,}`

as the decimal indicator, useMathJax = { tex: { digits: /^(?:[0-9]+(?:\{,\}[0-9]*)?|\{,\}[0-9]+)/ } };

- tags: 'none'
This controls whether equations are numbered and how. By default it is set to

`'none'`

to be compatible with earlier versions of MathJax where auto-numbering was not performed (so pages will not change their appearance). You can change this to`'ams'`

for equations numbered as the AMSmath package would do, or`'all'`

to get an equation number for every displayed equation.

- tagSide: 'right'
This specifies the side on which

`\tag{}`

macros will place the tags, and on which automatic equation numbers will appear. Set it to`'left'`

to place the tags on the left-hand side.

- tagIndent: "0.8em"
This is the amount of indentation (from the right or left) for the tags produced by the

`\tag{}`

macro or by automatic equation numbers.

- useLabelIds: true
This controls whether element IDs for tags use the

`\label`

name or the equation number. When`true`

, use the label, when`false`

, use the equation number.

- maxMacros: 10000
Because a definition of the form

`\def\x{\x} \x`

would cause MathJax to loop infinitely, the`maxMacros`

constant will limit the number of macro substitutions allowed in any expression processed by MathJax.

- maxBuffer: 5 * 1024
Because a definition of the form

`\def\x{\x aaa} \x`

would loop infinitely, and at the same time stack up lots of a’s in MathJax’s equation buffer, the`maxBuffer`

constant is used to limit the size of the string being processed by MathJax. It is set to 5KB, which should be sufficient for any reasonable equation.

- baseURL: (document.getElementsByTagName('base').length === 0) ?
- '' : String(document.location).replace(/#.*$/, ''))
This is the base URL to use when creating links to tagged equations (via

`\ref{}`

or`\eqref{}`

) when there is a`<base>`

element in the document that would affect those links. You can set this value by hand if MathJax doesn’t produce the correct link.

- formatError: (jax, err) => jax.formatError(err)
This is a function that is called when the TeX input jax reports a syntax or other error in the TeX that it is processing. The default is to generate an

`<merror>`

MathML element with the message indicating the error that occurred. You can override the function to perform other tasks, like recording the message, replacing the message with an alternative message, or throwing the error so that MathJax will stop at that point (you can catch the error using promises or a`try/carch`

block).

The remaining options are described in the Options Common to All Input Processors section.

## Developer Options

In addition to the options listed above, low-level options intended for developers include the following:

- FindTeX: null
The

`FindTeX`

object instance that will override the default one. This allows you to create a subclass of`FindTeX`

and pass that to the TeX input jax. A`null`

value means use the default`FindTeX`

class and make a new instance of that.

## TeX Extension Options

Several of the TeX extensions make additional options available in the
`tex`

block of your MathJax configuration. These are described
below. Note that the input/tex component, and the
combined components that load the TeX input jax, include a number of
these extensions automatically, so some these options will be
available by default.

For example, the configmacros package adds a `macros`

block to the `tex`

configuration block that allows you to pre-define
macros for use in TeX espressions:

```
MathJax = {
tex: {
macros: {
R: '\\mathbf{R}'
}
}
}
```

The options for the various TeX packages (that have options) are described in the links below:

## Setting Options from within TeX Expressions

It is sometimes convenient to be able to change the value of a TeX or
TeX extension option from within a TeX expression. For example, you
might want to change the tag side for an individual expression. The
setoptions extension allows you to do just that. It
defines a `\setOptions`

macro that allows you to change the values
of options for the TeX parser, or the options for a given TeX package.

Because this functionality can have potential adverse consequences on a page that allows community members to enter TeX notation, this extension is not loaded by default, and can’t be loaded by require{}. You must load it and add it to the tex package list explicitly in order to allow the options to be set. The extension has configuration parameters that allow you to control which packages and options can be modified from within a TeX expression, and you may wish to adjust those if you are using this macro in a community setting.