libplplot-dev 5.15.0+dfsg-8ubuntu2 (amd64 binary) in ubuntu focal

 PLplot is relatively small, portable, freely distributable, and is rich
 enough to satisfy most users. It has a wide range of plot types including
 line (linear, log), contour, 3D, fill, and almost 1000 characters
 (including Greek and mathematical) in its extended font set. The package
 is designed to make it easy to quickly get graphical output; only a
 handful of function calls is typically required. For more advanced use,
 virtually all aspects of plotting are configurable.
 .
 This package contains all that is needed for doing development in C, C++
 and Fortran with PLplot. Examples of programs for these languages are
 also included. For development in Tcl/Tk, Python and Java
 install the plplot-tcl-dev, python3-plplot
 and libplplot-java packages, respectively. This package also includes the
 OCaml and Lua examples. To use one of these languages you will also
 need to install the libplplot-xxx package for that language.