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: 
[This PPA](https://launchpad.net/%7Epicaso/+archive/octave) should solve your problem, provided you are running the latest 12.04.

Open Terminal `Ctrl-Alt-T` and type:

```

sudo apt-add-repository -y ppa:picaso/octave
sudo apt-get update 
sudo apt-get install octave
sudo apt-get install liboctave-dev 

```

---

For Ubuntu 20.04, see [this](https://askubuntu.com/a/206050/124466) answer.
The answer is quite simple. Go to the [Octave downloads website](http://ftp.gnu.org/gnu/octave/) and find the latest release of GNU Octave and download the .tar.gz file of it.

After this copy and paste the following terminal (CTRL+ALT+T) commands:

```
sudo apt-get build-dep octave
cd ~/Downloads
sudo mv octave-x.x.x.tar.gz ~
cd ~
tar xvf octave-x.x.x.tar.gz
cd octave-x.x.x
./configure
make
sudo make install

```

Where the 'x.x.x' refers to the version of GNU Octave you'd like to install, such as 3.6.3.