How can I download and install gnuplot for ubuntu 12.10? I can't find it on the software center or in repositories. Maybe I am not calling it right.
Strange. When I type "gnuplot" in the software center search, it's the first hit.
Anyway, you may try from the command line:
sudo apt-get install gnuplot
If this does't work either, you probably have some issues with the configuration of the package repository. That's rather a Linux/Ubuntu question than TeX related.