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11.7.3 LaTeX fragments

Going beyond symbols and sub- and superscripts, a full formula language is needed. Org mode can contain LaTeX math fragments, and it supports ways to process these for several export back-ends. When exporting to LaTeX, the code is obviously left as it is. When exporting to HTML, Org invokes the MathJax library (see Math formatting in HTML export) to process and display the math127. Finally, it can also process the mathematical expressions into images128 that can be displayed in a browser.

LaTeX fragments don’t need any special marking at all. The following snippets will be identified as LaTeX source code:

• Environments of any kind129. The only requirement is that the \begin and \end statements appear on a new line, at the beginning of the line or after whitespaces only.
• Text within the usual LaTeX math delimiters. To avoid conflicts with currency specifications, single ‘$’ characters are only recognized as math delimiters if the enclosed text contains at most two line breaks, is directly attached to the ‘$’ characters with no whitespace in between, and if the closing ‘$’ is followed by whitespace, punctuation or a dash. For the other delimiters, there is no such restriction, so when in doubt, use ‘$$...$$’ as inline math delimiters. For example: $$x=\sqrt{b}$$ If$a^2=b\$ and $$b=2$$, then the solution must be
either $$a=+\sqrt{2}$$ or $a=-\sqrt{2}$.


LaTeX processing can be configured with the variable org-export-with-latex. The default setting is t which means MathJax for HTML, and no processing for ASCII and LaTeX back-ends. You can also set this variable on a per-file basis using one of these lines:

#+OPTIONS: tex:t          Do the right thing automatically (MathJax)
#+OPTIONS: tex:nil        Do not process LaTeX fragments at all
#+OPTIONS: tex:verbatim   Verbatim export, for jsMath or so


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If you plan to use this regularly or on pages with significant page views, you should install MathJax on your own server in order to limit the load of our server.

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For this to work you need to be on a system with a working LaTeX installation. You also need the dvipng program or the convert, respectively available at http://sourceforge.net/projects/dvipng/ and from the imagemagick suite. The LaTeX header that will be used when processing a fragment can be configured with the variable org-format-latex-header.

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When MathJax is used, only the environments recognized by MathJax will be processed. When dvipng program or imagemagick suite is used to create images, any LaTeX environment will be handled.

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