libcneartree-dev 3.1.1-2.1 (arm64 binary) in ubuntu bionic

 Neartree is an API and a library for finding nearest neighbors among
 points in spaces of arbitrary dimensions. This package provides a C++
 template, TNear.h, and C library and header files for compiling
 programs using Neartree.
 .
 The library uses the Nearest Neighbor algorithm after Kalantari and
 McDonald, (IEEE Transactions on Software Engineering, v. SE-9, pp.
 631-634,1983) modified to use recursion instead of a double-linked tree
 and simplified so that it does less checking for things like is the
 distance to the right less than the distance to the left; it was found
 that these checks make little to no difference.