gnuplot-mode software package provides Gnuplot mode for Emacs, you can install in your Debian 8 (Jessie) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gnuplot-mode
gnuplot-mode is installed in your system.
Make ensure the gnuplot-mode package were installed using the commands given below,
$ sudo dpkg-query -l | grep gnuplot-mode *
You will get with gnuplot-mode package name, version, architecture and description in a table
| Distro | Debian 8 jessie |
| Section | Mathematics |
| Package | gnuplot-mode |
| Version | 1:0.7.0-1 |
| Description | Gnuplot mode for Emacs |
| Sub Section | Math |