Question: I want to install Octave on my Ubuntu LTS with `apt-get`. The problem is that the official repositories list only Octave 3.0 and Octave 3.2, whereas the latest Octave is Octave 3.6.

How do I update the repositories of apt-get to get Octave 3.6?

Answer: 
Just as an update: [this PPA](https://launchpad.net/~mtmiller/+archive/octave) (maintained by a member of the Debian Octave Group) provides the latest Octave for a range of Ubuntu versions.
Latest ppa is ppa:octave/stable.

<https://launchpad.net/~octave/+archive/ubuntu/stable>

This ppa is maitained by the "GNU Octave" team and has version 3.8.1 available for lucid and precise.