octave-plplot binary package in Ubuntu Oracular 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 Octave bindings for PLplot. It provides an
 almost drop-in replacement for the traditional Gnuplot graphical
 interface in Octave. Examples are also provided.

Source package