plplot-doc binary package in Ubuntu Focal riscv64

 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 the HTML, PDF, PostScript and info forms of the
 PLplot documentation. It also contains the man pages for the API
 functions.

Source package