gnuplot binary package in Ubuntu Focal amd64

 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. The X11-output
 is packaged in gnuplot-x11.
 .
 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 metapackage is to install a full-featured gnuplot (-qt, -x11 or -nox).

Source package