# LaTeX Math with Wikimedia Mathoid

The DMOJ platform is capable of rendering LaTeX math for constraints and formulas that may appear in problem statements. For example, this problem makes extensive use of this functionality to present crisp math rendering in browsers.

The DMOJ makes use of the Wikimedia Mathoid project to render math.

## Installing Mathoid

Follow the installation instructions of Mathoid. Moving forward, we'll assume that you are running Mathoid on localhost:8888.

## Configuring DMOJ to use Mathoid

Assuming Mathoid is installed, configuring DMOJ to generate math with it requires the addition of a few lines to local_settings.py.

# The URL Mathoid is running on
MATHOID_URL = 'http://localhost:8888'
# A directory accessible by the user running Mathoid, as well as the web (nginx) user.
# For optimal performance, change this to something more persistant than /tmp
MATHOID_CACHE_ROOT = '/tmp/mathoid_cache'
# The URL base MATHOID_CACHE_ROOT is configured to be served under in your webserver. For
# example, if /tmp/mathoid_cache/render.png exists, example.com/mathoid/render.png should
# serve it.
MATHOID_CACHE_URL = '//example.com/mathoid/'


Restart DMOJ for the changes to take effect. After restarting, you may have to purge Django's cache before seeing any changes.

## Using Mathoid math in problem statements

A snippet of a problem statement using Mathoid to render math is shown below.

The Fibonacci sequence is a well known sequence of numbers in which

$$F(n) = \begin{cases} 0, & \text{if } n = 0 \\ 1, & \text{if } n = 1 \\ F(n-2) + F(n-1), & \text{if } n \ge 2 \end{cases}$$

Given a number ~N~ ~(1 \le N \le 10^{19})~, find the ~N^{th}~ Fibonacci number, modulo ~1\,000\,000\,007~ ~(= 10^9 + 7)~.<br/>
**Note:** For 30% of the marks of this problem, it is guaranteed that ~(1 \le N \le 1\,000\,000)~.