libann0 binary package in Ubuntu Focal arm64

 ANN is a library written in C++, which supports data structures and
 algorithms for both exact and approximate nearest neighbor searching
 in arbitrarily high dimensions. ANN assumes that distances
 are measured using any class of distance functions called Minkowski
 metrics. These include the well known Euclidean distance, Manhattan
 distance, and max distance. ANN performs quite efficiently for point
 sets ranging in size from thousands to hundreds of thousands, and in
 dimensions as high as 20.

Source package