# LaTeX & MathJax basic tutorial – Symbols & Cases

## Symbols

In general, you have to search in long tables about a specific symbol you’re looking for, things like $\Psi$, $\delta$, $\zeta$, $\ge$, $\subseteq$ … And it turns out that this operation can be frustrating and time consuming, which can cause the buddy to abandon writing the complete $\LaTeX$ sentence in his answer, or in some cases, the complete answer itself.

That’s why the tool that I will present you in this post was conceived. Basically, it is a $\LaTeX$ handwritten symbol recognition. Example in image:

Here is the website: Detexify²
No more frustration.

## Definitions by cases (piecewise functions)

Use \begin{cases}…\end{cases}. End each case with a \\, and use &  before parts that should be aligned.

For example, you get this:

$$f(n) = \begin{cases} n/2, & \text{if n is even} \\ 3n+1, & \text{if n is odd} \end{cases}$$

by writing this:

The brace can be moved to the right:
$$\left. \begin{array}{l} \text{if n is even:}& n/2\\ \text{if n is odd:}& 3n+1 \end{array} \right\} =f(n)$$
by writing this:

To get a larger vertical space between cases we can use \\[2ex] instead of \\. For example, you get this:

$$f(n) = \begin{cases} \frac{n}{2}, & \text{if n is even} \\[2ex] 3n+1, & \text{if n is odd} \end{cases}$$

by writing this:

(An ‘ex’ is a length equal to the height of the letter x; 2ex here means the space should be two exes high.)