I am attempting to write out the basic process for finding the absolute value of some number.

In ASCII, this is what I am attempting to write.

```
|X| = {
        x  if x > 0
        0  if x = 0
        -x if x < 0
      }

```

This is what I have so far.

```
\begin{equation}
\left|x\right| = \biggl\{ x\ if\ x > 0 \biggr\}
\end{equation}

```

I cannot figure out how to add the vertical spacing to allow the other two lines.