Building Octave on Slackware
GNU Octave is contained in the SlackBuilds repository, which contains building receipts for several software packages. The SlackBuilds Howto page describes in detail, how to use such a receipt.
The receipt for Octave has dependencies, which aren't automatically resolved and are listed in the README file of the Octave receipt.
Those dependencies are:
Note that there are further dependencies which are optional, e.g., GraphicsMagick. Another more general list of dependencies is given in the Building wiki page.