<
<p style="font-size:x-large;">
Inline equations, as for instance the classic $\Delta = b^2-4ac$ and
$x\_{1,2} = \frac{-b\pm\sqrt{\Delta}}{2a}$, or display equations as this one :
$$ J\_\alpha(x) = \sum\limits\_{m=0}^\infty \frac{(-1)^m}{m! \, \Gamma(m + \alpha + 1)}{\left({\frac{x}{2}}\right)}^{2 m + \alpha} $$
</p>
## From a classic math book
But a less classic exercise about [Hölder functions](https://en.wikipedia.org/wiki/H%C3%B6lder_condition)
(more precisely, *Exercice 7*, Chapter 4.5, page 267, of the [Gourdon, "*Les maths en tête : Analyse*", $2^\text{nd}$ edition](http://www.amazon.fr/gp/product/2729837590) book).
<p style="font-size:x-large;">
$$ 4 \sum\_{n=1}^{+\infty} \rho\_n^2 \sin^2 nh = \frac{1}{2\pi} \int\_{-\pi}^{\pi}\lvert f(x+h) - f(x-h)\rvert^2 dx. $$
</p>
## How-to ?
The previous equation is simply included in the Markdown code part as basic some $\LaTeX2e{}$ code :
> ```latex
$$ 4 \sum\_{n=1}^{+\infty} \rho\_n^2 \sin^2 nh = \frac{1}{2\pi} \int\_{-\pi}^{\pi}|f(x+h) - f(x-h)|^2 dx. $$
```
***
## Yes, it is as simple as adding *one line at the bottom*
You just have to load [MathJax](http://www.mathjax.org/) (as described [here](http://docs.mathjax.org/en/latest/configuration.html))
from the bottom of a *StrapDown*-flavored page, for instance from the default *CDN* :
> ```html
<script type="text/javascript" src="//cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
```
You can consult [a second example](example4.html) to see some more advanced examples of LaTeX equations rendered with MathJax.
### A better solution?
From version 0.5, you can import MathJax in an even *quicker* way: you just have to add ``&mathjax=yes`` to the URL used to import [``strapdown.min.js``](index.html).
See [the first paragraph of this third example](example5.html) to see this.
***
# Warning
Be aware of the following limitations :
## Escape the underscore ('``_``')
The [StrapDown.js](//lbesson.bitbucket.io/md/index.html) text processor interprets
underscores (the '``_``' symbol) as underline markup (like _this_),
so be sure to escape the '``_``' in the $\LaTeX2e{}$ code.
A *bad looking* example could be ``$\mathcal{M}_{n,m}(\mathbb{F_9})$``
(which is **badly displayed** as $\mathcal{M}_{n,m}(\mathbb{F_9})$). _Ugly_ right ?
Escape the '``_``' in the previous code to get ``$\mathcal{M}\_{n,m}(\mathbb{F\_9})$`` :
now it is **nicely displayed** as $\mathcal{M}\_{n,m}(\mathbb{F\_9})$.
## Escape some others Markdown markup code ('``*``', '``**``' or '``#``')
The previous limitation is also true for other symbols, used for *Markdown as markup* and for *LaTeX as symbols*.
An example could be ``$[ u^*; v^*](x)$`` (which is badly displayed as $[ u^*; v^*](x)$),
which becomes ``$\[ u^\*; v^\*\]\(x\)$`` (now it is nicely displayed as $\[ u^\*; v^\*\]\(x\)$).
A pretty good rule of thumb can be to **escape every Markdown markup symbols** in LaTeX code.
Feel free to refresh your mind about which symbols are used as elements of the Markdown syntax
with [this page](http://daringfireball.net/projects/markdown/syntax#list),
or [this one on Wikipedia](https://en.wikipedia.org/wiki/Markdown).
## Escape the backslash ('``\``')
The backslash symbol, already escaped by an backslash ('``\``')
is used in LaTeX to force a new line. It is usually used in aligned equations,
as shown in the Lorenz Equations [here](example4.html).
You should also escape the backslash, by typing ``\\`` where you would have
used a simple ``\`` in LaTeX.
***
## See also
+ [This page](http://perso.crans.org/besson/math.html) shows how to use MathJax on a [Sphinx](http://sphinx-doc.org/) project.
+ [This script (strapdown2pdf)](strapdown2pdf.html) to print to PDF a *StrapDown*-powered web page.
It comes with a limited support of LaTeX (still not perfect).
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