I'm new to Matlab, and I'm trying to unscrabble the code [here](http://www-scf.usc.edu/~mohammab/codes/iLasso.m). In particular, I'm wondering what this line does:

```
ti = (Series{1}(2, i) - L*Dt):Dt:(Series{1}(2, i)-Dt);

```

In particular, what does the colon do? I found [this explanation](http://www.tutorialspoint.com/matlab/matlab_syntax.htm):

[![enter image description here](https://i.stack.imgur.com/SqwjY.png)](https://i.stack.imgur.com/SqwjY.png)

But to me this doesn't tell me what it's doing here. Similarly, I'm not even clear on what `Series{1}(2, i) - L*Dt` produces. I get that normally the answer would be 'try it out', but I don't have access to Matlab and so would appreciate any comments or advice.

Thank you.