Rust code:

Copyright 2020 Rusty Conover rusty@conover.me
MIT License


hilbert.c and hilbert.h:

This software is copyrighted by Rice University.  It may be freely copied,
modified, and redistributed, provided that the copyright notice is
preserved on all copies.

There is no warranty or other guarantee of fitness for this software,
it is provided solely "as is".  Bug reports or fixes may be sent
to the author, who may or may not act on them as he desires.

You may include this software in a program or other software product,
but must display the notice:

Hilbert Curve implementation copyright 1998, Rice University
in any place where the end-user would see your own copyright.

If you modify this software, you should include a notice giving the
name of the person performing the modification, the date of modification,
and the reason for such modification.