This repository contains a simple implementation of [Z-order curves][1] along
with `litmax` and `bigmin` calculations as described in the paper
["Multidimensional Range Search in Dynamically Balanced Trees"][2] by H. Tropf
and H. Herzog (Angewandte Informatik 2/1981, pp. 71-77).

[1]: https://en.wikipedia.org/wiki/Z-order_curve
[2]: http://www.vision-tools.com/h-tropf/multidimensionalrangequery.pdf