Install ROOT on ubuntu
The original instructions can be found here.
It's really very simple. Just add a new source list file
# sudo gedit /etc/apt/sources.list.d/root.list
Put the following lines in the file and save
# ROOT packets for Gutsy Gibbon deb http://mirror.phy.bnl.gov/debian-root/ubuntu gutsy main contrib non-free
If you haven't done it yet, you'll have to install the author's signature.
gpg --keyserver subkeys.pgp.net --recv-keys 6620D4F5 gpg --export 6620D4F5 | sudo apt-key add -
At the next update you will find a new source in synaptic: mirror.phy.bnl.gov/main and a new set of packages. Just install the metapackage named root-system.
Please remember that minuit is not included by the root-system metapackage, so if you want to make some fit you'll have to explicitely install it.