Gsl 1.12 .deb packages for Ubuntu Hardy 8.04 are available on my backports PPA. To install it:

Copy the lines below and add them to your system’s software sources. (Read about installing) deb http://ppa.launchpad.net/daniele.domenichelli/backports/ubuntu hardy main deb-src http://ppa.launchpad.net/daniele.domenichelli/backports/ubuntu hardy main

Import public key for my PPA: sudo apt-key adv –keyserver keyserver.ubuntu.com –recv-keys 9D0C02D0

[…]