# TeX and LaTeX math delimiters¶

By default, the TeX processor uses the LaTeX math delimiters, which are $$...$$ for in-line math, and $...$ for displayed equations. It also recognizes the TeX delimiters $$...$$ for displayed equations, but it does not define $...$ as in-line math delimiters. That is because dollar signs appear too often in non-mathematical settings, which could cause some text to be treated as mathematics unexpectedly. For example, with single-dollar 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 single dollar signs for in-line math mode, you must enable that explicitly in your configuration:

window.MathJax = {
tex: {
inlineMath: [['$', '$'], ['\$$', '\$$']]
}
};


You can use \$ to prevent a dollar sign from being treated as a math delimiter within the text of your web page, e.g., use “… the cost is$2.50 for the first one, and \$2.00 for each additional one …” to prevent these dollar signs from being used as math delimiters in a web page where dollar signs have been configured to be in-line delimiters.

Note that, as opposed to true LaTeX, MathJax processes all environments when wrapped inside math delimiters, even those like $$...$$ that are supposed to be used to initiate math mode. By default, MathJax will also render all environments outside of delimiters, e.g., \begin{matrix}...\end{matrix} would be processed even if it is not in math mode delimiters, though you are encouraged to use proper delimiters for these cases to make your files more compatible with actual LaTeX. This functionality can be controlled via the processEnvironments option in the tex configuration options.

See the tex configuration options page, for additional configuration parameters that you can specify for the TeX input processor.