Print Bibliography Undefined Control Sequence Mathbb
The support for TeX and LaTeX in MathJax consists of two parts: the tex2jax preprocessor, and the TeX input processor. The first of these looks for mathematics within your web page (indicated by math delimiters like ) and marks the mathematics for later processing by MathJax. The TeX input processor is what converts the TeX notation into MathJax’s internal format, where one of MathJax’s output processors then displays it in the web page.
The tex2jax preprocessor can be configured to look for whatever markers you want to use for your math delimiters. See the tex2jax configuration options section for details on how to customize the action of tex2jax.
The TeX input processor handles conversion of your mathematical notation into MathJax’s internal format (which is essentially MathML), and so acts as a TeX to MathML converter. The TeX input processor has few configuration options (see the TeX options section for details), but it can also be customized through the use of extensions that define additional functionality (see the TeX and LaTeX extensions below).
Differences¶
Since MathJax renders for the web and TeX is a print layout engine, there are natural limitations of which parts of TeX can be supported in a reasonable way. Accordingly, there are several differences between “real” TeX/LaTeX systems and MathJax’s TeX Input.
First and foremost, the TeX input processor implements only the mathmode macros of TeX and LaTeX, not the textmode macros. MathJax expects that you will use standard HTML tags to handle formatting the text of your page; it only handles the mathematics. So, for example, MathJax does not implement or or other textmode macros or environments. You must use HTML to handle such formatting tasks. If you need a LaTeXtoHTML converter, you should consider other options.
There are two exception to this rule. First, MathJax supports the ref macro outside of mathmode. Second, MathJax supports some macros that add text within mathmode (such as text{}) as well as $…$ within such macros (to switch back into mathmode) and`$` to escape.
Second, some features in MathJax might be necessarily limited. For example, MathJax only implements a limited subset of the environment’s preamble, i.e., only the , , , and characters alongside for dashed lines; everything else is ignored.
TeX and LaTeX math delimiters¶
By default, the tex2jax preprocessor defines the LaTeX math delimiters, which are for inline math, and for displayed equations. It also defines the TeX delimiters for displayed equations, but it does not define as inline math delimiters. That is because dollar signs appear too often in nonmathematical settings, which could cause some text to be treated as mathematics unexpectedly. For example, with singledollar delimiters, “… the cost is $2.50 for the first one, and $2.00 for each additional one …” would cause the phrase “2.50 for the first one, and” to be treated as mathematics since it falls between dollar signs. For this reason, if you want to use singledollars for inline math mode, you must enable that explicitly in your configuration:
Note that if you do this, you may want to also set to , as in the example above, so that you can use to prevent a dollar sign from being treated as a math delimiter within the text of your web page. (Note that within TeX mathematics, always has this meaning; only affects the treatment of the opening math delimiter.)
Note that, as opposed to true LaTeX, MathJax processes all environments when wrapped inside math delimiters. By defaut, MathJax will also render all environments outside of delimiters; this can be controlled via the option in the tex2jax configuration options.
See the file, or the tex2jax configuration options page, for additional configuration parameters that you can specify for the tex2jax preprocessor, which is the component of MathJax that identifies TeX notation within the page.
TeX and LaTeX in HTML documents¶
Keep in mind that your mathematics is part of an HTML document, so you need to be aware of the special characters used by HTML as part of its markup. There cannot be HTML tags within the math delimiters (other than ) as TeXformatted math does not include HTML tags. Also, since the mathematics is initially given as text on the page, you need to be careful that your mathematics doesn’t look like HTML tags to the browser (which parses the page before MathJax gets to see it). In particular, that means that you have to be careful about things like lessthan and greaterthan signs ( and ), and ampersands (), which have special meaning to the browsers. For example,
will cause a problem, because the browser will think is the beginning of a tag named (even though there is no such tag in HTML). When this happens, the browser will think the tag continues up to the next in the document (typically the end of the next actual tag in the HTML file), and you may notice that you are missing part of the text of the document. In the example above, the “” will not be displayed because the browser thinks it is part of the tag starting at . This is one indication you can use to spot this problem; it is a common error and should be avoided.
Usually, it is sufficient to simply put spaces around these symbols to cause the browser to avoid them, so
should work. Alternatively, you can use the HTML entities , and to encode these characters so that the browser will not interpret them, but MathJax will. E.g.,
Finally, there are and macros defined to make it easier to enter and using TeXlike syntax:
Keep in mind that the browser interprets your text before MathJax does.
Another source of difficulty is when MathJax is used in content management systems that have their own document processing commands that are interpreted before the HTML page is created. For example, many blogs and wikis use formats like Markdown to allow you to create the content of you pages. In Markdown, the underscore is used to indicate italics, and this usage will conflict with MathJax’s use of the underscore to indicate a subscript. Since Markdown is applied to the page first, it will convert your subscripts markers into italics (inserting tags into your mathematics, which will cause MathJax to ignore the math).
Such systems need to be told not to modify the mathematics that appears between math delimiters. That usually involves modifying the contentmanagement system itself, which is beyond the means of most page authors. If you are lucky, someone else will already have done this for you, and you can find a MathJax plugin for your system on the MathJaxInUse page.
If there is no plugin for your system, or if it doesn’t handle the subtleties of isolating the mathematics from the other markup that it supports, then you may have to “trick” it into leaving your mathematics untouched. Most contentmanagement systems provide some means of indicating text that should not be modified (“verbatim” text), often for giving code snippets for computer languages. You may be use that to enclose your mathematics so that the system leaves it unchanged and MathJax can process it. For example, in Markdown, the backtick () is used to mark verbatim text, so
may be able to protect the underscores from being processed by Markdown.
Some contentmanagement systems use the backslash () as a special character for “escaping” other characters, but TeX uses this character to indicate a macro name. In such systems, you may have to double the backslashes in order to obtain a single backslash in your HTML page. For example, you may have to do
to get an array with the four entries a, b, c, and d. Note in particular that if you want you will have to double both backslashes, giving .
Finally, if you have enabled single dollarsigns as math delimiters, and you want to include a literal dollar sign in your web page (one that doesn’t represent a math delimiter), you will need to prevent MathJax from using it as a math delimiter. If you also enable the configuration parameter, then you can use in the text of your page to get a dollar sign (without the backslash) in the end. Alternatively, you use something like to isolate the dollar sign so that MathJax will not use it as a delimiter.
Defining TeX macros¶
You can use the , , , , , and commands to create your own macros and environments. Unlike actual TeX, however, in order for MathJax to process such definitions, they must be enclosed in math delimiters (since MathJax only processes macros in mathmode). For example
would define to produce a boldfaced “R”, and to put its argument into bold face. Both definitions would be available throughout the rest of the page.
You can include macro definitions in the Macros section of the TeX blocks of your configuration, but they must be represented as JavaScript objects. For example, the two macros above can be predefined in the configuration by
Here you give the macro as a name:value pair, where the name is the name of the control sequence (without the backslash) that you are defining, and value is either the replacement string for the macro (when there are no arguments) or an array consisting of the replacement string followed by the number of arguments for the macro and, optionally, default values for optional arguments.
Note that the replacement string is given as a JavaScript string literal, and the backslash has special meaning in JavaScript strings. So to get an actual backslash in the string you must double it, as in the examples above.
If you have many such definitions that you want to use on more than one page, you could put them into a configuration file that you can load along with the main configuration file. For example, you could create a file in called that contains your macro definitions:
and then load it along with your main configuration file on the script that loads :
If you are using the CDN, you can make a local configuration file on your own server, and load MathJax itself from the CDN and your configuration file from your server. See Using a Local Configuration File with the CDN for details.
Automatic Equation Numbering¶
New in MathJax v2.0 is the ability to have equations be numbered automatically. This functionality is turned off by default, so that pages don’t change when you update from v1.1 to v2.0, but it is easy to configure MathJax to produce automatic equation numbers by adding:
to your page just before the tag that loads itself.
Equations can be numbered in two ways: either number the AMSmath environments as LaTeX would, or number all displayed equations (the example above uses AMSstyle numbering). Set to if you want every displayed equation to be numbered. You can use or to prevent individual equations from being numbered, and can be used to override the usual equation number with your own symbol instead.
Note that the AMS environments come in two forms: starred and unstarred. The unstarred versions produce equation numbers (when is set to ) and the starred ones don’t. For example
will be numbered, while
won’t be numbered (when is ).
You can use to give an equation an identifier that you can use to refer to it later, and then use or within your document to insert the actual equation number at that location, as a reference. For example,
includes a labeled equation and a reference to that equation. Note that references can come before the corresponding formula as well as after them. See the equation numbering pages in the MathJax examples at for more examples.
You can configure the way that numbers are displayed and how the references to them are made using parameters in the block of your configuration. See the TeX configuration options page for more details.
If you are using automatic equation numbering and modifying the page dynamically, you can run into problems due to duplicate labels. See Reset Automatic Equation Numbering for how to address this.
TeX and LaTeX extensions¶
While MathJax includes nearly all of the Plain TeX math macros, and many of the LaTeX macros and environments, not everything is implemented in the core TeX input processor. Some lessused commands are defined in extensions to the TeX processor. MathJax will load some extensions automatically when you first use the commands they implement (for example, the and macros are implemented in the extension, but MathJax loads this extension itself when you use those macros). Not all extensions are set up to load automatically, however, so you may need to request some extensions explicitly yourself.
To enable any of the TeX extensions, simply add the appropriate string (e.g., ) to the extensions array in the block of your configuration. If you use one of the combined configuration files, like , this will already include several of the extensions automatically, but you can include others using a mathjax configuration script prior to loading MathJax. For example
will load the autobold TeX extension in addition to those already included in the configuration file.
You can also load these extensions from within a math expression using the nonstandard macro. For example
would load the color extension into the page. This way you you can load extensions into pages that didn’t load them in their configurations (and prevents you from having to load all the extensions into all pages even if they aren’t used).
It is also possible to create a macro that will autoload an extension when it is first used (under the assumption that the extension will redefine it to perform its true function). For example
would declare the , , , and macros to load the cancel extension (where they are actually defined). Whichever is used first will cause the extension to be loaded, redefining all four to their proper values. Note that this may be better than loading the extension explicitly, since it avoids loading the extra file on pages where these macros are not used. The sample autoloading macros example page shows this in action. The autoloadall extension below defines such macros for all the extensions so that if you include it, MathJax will have access to all the macros it knows about.
The main extensions are described below.
Action¶
The action extension gives you access to the MathML element. It defines three new nonstandard macros:
Use (in math mode) as tooltip for .
Use (in text mode) as tooltip for .
Show , and when clicked, show , and so on. When the last one is clicked, go back to math1.
To use this extension in your own configurations, add it to the extensions array in the TeX block.
This extension is not included in any of the combined configurations, and will not be loaded automatically, so you must include it explicitly in your configuration if you wish to use these commands.
AMSmath and AMSsymbols¶
The AMSmath extension implements AMS math environments and macros, and the AMSsymbols extension implements macros for accessing the AMS symbol fonts. These are already included in the combined configuration files that load the TeX input processor. To use these extensions in your own configurations, add them to the extensions array in the TeX block.
See the list of control sequences at the end of this document for details about what commands are implemented in these extensions.
If you are not using one of the combined configuration files, the AMSmath extension will be loaded automatically when you first use one of the math environments it defines, but you will have to load it explicitly if you want to use the other macros that it defines. The AMSsymbols extension is not loaded automatically, so you must include it explicitly if you want to use the macros it defines.
Both extensions are included in all the combined configuration files that load the TeX input processor.
AMScd¶
The AMScd extensions implements the CD environment for commutative diagrams. See the AMScd guide for more information on how to use the CD environment.
To use this extension in your own configurations, add it to the extensions array in the TeX block.
Alternatively, if the extension hasn’t been loaded in the configuration, you can use to load it from within a TeX expression. Note that you only need to include this once on the page, not every time the CD environment is used.
This extension is not included in any of the combined configurations, and will not be loaded automatically, so you must include it explicitly in your configuration if you wish to use these commands.
Autobold¶
The autobold extension adds around mathematics that appears in a section of an HTML page that is in bold.
This extension is not loaded by the combined configuration files.
BBox¶
The bbox extension defines a new macro for adding background colors, borders, and padding to your math expressions.
puts a bounding box around using the provided . The options can be one of the following:
 A color name used for the background color.
 A dimension (e.g., ) to be used as a padding around the mathematics (on all sides).
 Style attributes to be applied to the mathematics (e.g., ).
 A combination of these separated by commas.
Here are some examples:
This extension is not included in any of the combined configurations, but it will be loaded automatically, so you do not need to include it in your extensions array.
Begingroup¶
The begingroup extension implements commands that provide a mechanism for localizing macro defintions so that they are not permanent. This is useful if you have a blog site, for example, and want to isolate changes that your readers make in their comments so that they don’t affect later comments.
It defines two new nonstandard macros, and , that are used to start and stop a local namespace for macros. Any macros that are defined between the and will be removed after the is executed. For example, if you put at the top of each reader’s comments and at the end, then any macros they define within their response will be removed after it is processed.
In addition to these two macros, the begingroup extension defines the standard and control sequences from TeX. (The , , , and control sequences are already defined in the core TeX input jax.)
To use this extension in your own configurations, add it to the extensions array in the TeX block.
This extension is not included in any of the combined configurations, and will not be loaded automatically, so you must include it explicitly in your configuration if you wish to use these commands.
Cancel¶
The cancel extension defines the following macros:
Strikeout from lower left to upper right.
Strikeout from upper left to lower right.
Strikeout with an “X”.
Strikeout with an arrow going to .
To use this extension in your own configurations, add it to the extensions array in the TeX block.
This extension is not included in any of the combined configurations, and will not be loaded automatically, so you must include it explicitly in your configuration if you wish to use these commands.
Color¶
The command in the core TeX input jax is not standard in that it takes the mathematics to be colored as one of its parameters, whereas the LaTeX command is a switch that changes the color of everything that follows it.
The color extension changes the command to be compatible with the LaTeX implementation, and also defines , , and , as in the LaTeX color package. It defines the standard set of colors (Apricot, Aquamarine, Bittersweet, and so on), and provides the RGB and greyscale color spaces in addition to named colors.
To use this extension in your own configurations, add it to the extensions array in the TeX block.
This extension is not included in any of the combined configurations, and will not be loaded automatically, so you must include it explicitly in your configuration if you wish to use these commands, and have be compatible with LaTeX usage.
Enclose¶
The enclose extension gives you access to the MathML element for adding boxes, ovals, strikethroughs, and other marks over your mathematics. It defines the following nonstandard macro:
Where is a commaseparated list of MathML notations (e.g., , , , , etc.), are MathML attribute values allowed on the element (e.g., , ), and is the mathematics to be enclosed. See the MathML 3 specification for more details on .
For example
To use this extension in your own configurations, add it to the extensions array in the TeX block.
This extension is not included in any of the combined configurations, and will not be loaded automatically, so you must include it explicitly in your configuration if you wish to use these commands.
Extpfeil¶
The extpfeil extension adds more macros for producing extensible arrows, including , , , , , and a nonstandard for creating your own extensible arrows. The latter has the form
where is the new control sequence name to be defined, and are integers representing the amount of space (in suitably small units) to use at the left and right of text that is placed above or below the arrow, and is a number representing a unicode character position in either decimal or hexadecimal notation.
For example
defines an extensible right harpoon with barb up. Note that MathJax knows how to stretch only a limited number of characters, so you may not actually get a stretchy character this way.
To use this extension in your own configurations, add it to the extensions array in the TeX block.
This extension is not included in any of the combined configurations, and will not be loaded automatically, so you must include it explicitly in your configuration if you wish to use these commands.
HTML¶
The HTML extension gives you access to some HTML features like styles, classes, element ID’s and clickable links. It defines the following nonstandard macros:
Makes be a link to the page given by .
Attaches the CSS class to the output associated with when it is included in the HTML page. This allows your CSS to style the element.
Attaches an id attribute with value to the output associated with when it is included in the HTML page. This allows your CSS to style the element, or your javascript to locate it on the page.
Adds the give declarations to the element associated with .
For example:
This extension is not included in any of the combined configurations, but it will be loaded automatically when any of these macros is used, so you do not need to include it explicitly in your configuration.
mhchem¶
The mhchem extensions implements the , , and chemical equation macros of the LaTeX mhchem package. See the mhchem CTAN page for more information and a link to the documentation for mhchem.
For example
To use this extension in your own configurations, add it to the extensions array in the TeX block.
This extension is not included in any of the combined configurations, and will not be loaded automatically, so you must include it explicitly in your configuration if you wish to use these commands.
Beginning with v2.7, the extension provides a configuration option to switch to mhchem v3, a complete refactor of mhchem contributed by the author of the original LaTeX package.
You can control this behavior using the value which defaults to .
noErrors¶
The noErrors extension prevents TeX error messages from being displayed and shows the original TeX code instead. You can configure whether the dollar signs are shown or not for inline math, and whether to put all the TeX on one line or use multiple lines (if the original text contained line breaks).
This extension is loaded by all the combined configuration files that include the TeX input processor. To enable the noErrors extension in your own configuration, or to modify its parameters, add something like the following to your call:
Displaystyle math is always shown in multiline format, and without delimiters, as it will already be set off in its own centered paragraph, like standard display mathematics.
The default settings place the invalid TeX in a multiline box with a black border. If you want it to look as though the TeX is just part of the paragraph, use
You may also wish to set the font family or other CSS values here.
If you are using a combined configuration file that loads the TeX input processor, it will also load the noErrors extension automatically. If you want to disable the noErrors extension so that you receive the normal TeX error messages, use the following configuration:
Any math that includes errors will be replaced by an error message indicating what went wrong.
noUndefined¶
The noUndefined extension causes undefined control sequences to be shown as their macro names rather than generating error messages. So would display as an “X” with a subscript consisting of the text in red.
This extension is loaded by all the combined configuration files that include the TeX input processor. To enable the noUndefined extension in your own configuration, or to modify its parameters, add something like the following to your call:
The setting specifies attributes to apply to the element that encodes the name of the undefined macro. The default values set to , but do not set any other attributes. This example sets the background to a light pink, and reduces the font size slightly.
If you are using a combined configuration file that loads the TeX input processor, it will also load the noUndefined extension automatically. If you want to disable the noUndefined extension so that you receive the normal TeX error messages for undefined macros, use the following configuration:
Any math that includes an undefined control sequence name will be replaced by an error message indicating what name was undefined.
Unicode support¶
The unicode extension implements a extension to TeX that allows arbitrary unicode code points to be entered in your mathematics. You can specify the height and depth of the character (the width is determined by the browser), and the default font from which to take the character.
Examples:
Once a size and font are provided for a given unicode point, they need not be specified again in subsequent calls for that character.
The result of will have TeX class ORD (i.e., it will act like a variable). Use , , etc., to specify a different class.
Note that a font list can be given in the macro, but Internet Explorer has a buggy implementation of the CSS attribute where it only looks in the first font in the list that is actually installed on the system, and if the required glyph is not in that font, it does not look at later fonts, but goes directly to the default font as set in the InternetOptions/Font panel. For this reason, the default font list for the macro is , so if the user has STIX fonts, the symbol will be taken from that (almost all the symbols are in STIXGeneral), otherwise MathJax tries Arial Unicode MS.
The unicode extension is loaded automatically when you first use the macro, so you do not need to add it to the extensions array. You can configure the extension as follows:
Autoloadall¶
The autoloadall extension predefines all the macros from the extensions above so that they autoload the extensions when first used. A number of macros already do this, e.g., , but this extension defines the others to do the same. That way MathJax will have access to all the macros that it knows about.
To use this extension in your own configurations, add it to the extensions array in the TeX block.
This extension is not included in any of the combined configurations, and will not be loaded automatically, so you must include it explicitly in your configuration if you wish to use these commands.
Note that autoloadall redefines to be the one from the color extension (the LaTeXcompatible one rather than the nonstandard MathJax version). This is because and autoload the color extension, which will cause to be redefined, and so for consistency, is redefined immediately.
If you wish to retain the original definition of , then use the following
Supported LaTeX commands¶
This is a long list of the TeX macros supported by MathJax. If the macro is defined in an extension, the name of the extension follows the macro name. If the extension is in brackets, the extension will be loaded automatically when the macro or environment is first used.
More complete details about how to use these macros, with examples and explanations, is available at Carol Fisher’s TeX Commands Available in MathJax page.
Symbols¶
A¶
B¶
C¶
D¶

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