Install gnuplot-doc by entering the following commands in the terminal:
sudo apt update sudo apt install gnuplot-doc
Description:
Command-line driven interactive plotting program. Doc-package
Gnuplot is a portable command-line driven interactive data and function plotting utility that supports lots of output formats, including drivers for many printers, (La)TeX, (x)fig, Postscript, and so on. . Data files and self-defined functions can be manipulated by the internal C-like language. Can perform smoothing, spline-fitting, or nonlinear fits, and can work with complex numbers. . This package contains the additional documentation.
Homepage: http://gnuplot.sourceforge.net/
Version: 5.2.2+dfsg1-2ubuntu1
Section: universe/doc