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At the following link in the MathJax documentation it lists the supported LaTeX symbols alphabetically that it supports, followed by the set of supported environments...


My question is where are each of these symbols/enviornments described and documented?

For example, where is the definitive description of the \above symbol ?

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Is the focus here MathJax or the more general syntax for math mode commands for (La)TeX? The latter is on-topic, but MathJax-specifics are off-topic as MathJax does not actually use TeX, only LaTeX-like math commands. – Joseph Wright Mar 25 '12 at 9:13
The commands and their usage are explained in detail in this page that is linked to the page you mentioned. – egreg Mar 25 '12 at 9:16
The advantage of just typing TeX equations in html that MathJax provides is so awesome that it never occurred to me that this might be off-topic. I assumed that the original question was aimed at extending MathJax support for LaTeX. I think egreg's answer was more appropriate. – Scott Prahl Mar 25 '12 at 20:17
@JosephWright: Sorry Joseph I disagree. The LaTeX-like features of MathJax are most certainly a TeX-related tool, and as such are on topic at tex.stackexchange.com, as per point 4 of FAQ. – Andrew Tomazos Mar 25 '12 at 20:40
@user1131467: No, it's not really a TeX-related tool, because it doesn't use Tex or is used together with it. It only uses a subset of the TeX syntax, plus maybe some extra things. A question about the description of LaTeX commands is on-topic, but MathJax documentation would be off-topic. Now you ask about a description for TeX commands (which is on-topic) but for a different software (off-topic), so your question is kind of in the gray area. – Martin Scharrer Mar 26 '12 at 14:36
up vote 4 down vote accepted

The Web page


has a very detailed explanation of each LaTeX command that is interpreted by MathJax.

The commands are of course explained in the LaTeX manual or in many user's guide; the commands that are labeled "AMS" are described in the documentation of amsmath.

A particularly recommended guide about math in LaTeX is "Math mode" by Herbert Voß (although more focused on usage in LaTeX).

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The definitive answers are in the JavaScript source code. The best way to examine the source is to download the source from GitHub

git clone http://github.com/mathjax/MathJax

Once you have the source files, then it is possible to see exactly how \above is implemented and you'll find that \above is defined in unpacked/jax/input/TeX/jax.js as 'Over', which in turn is implemented using the following JavaScript

Over: function (name,open,close) {
  var mml = STACKITEM.over().With({name: name});
  if (open || close) {
    mml.open = open; mml.close = close;
  } else if (name.match(/withdelims$/)) {
    mml.open  = this.GetDelimiter(name);
    mml.close = this.GetDelimiter(name);
  if (name.match(/^\\above/)) {mml.thickness = this.GetDimen(name)}
  else if (name.match(/^\\atop/) || open || close) {mml.thickness = 0}

which is pretty inscrutable. Simpler TeX constructs like \alpha are simply mapped to the corresponding unicode value

alpha:        '03B1',
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