I have prepared a resolution for issue MATH-1284 ( https://issues.apache.org/jira/browse/MATH-1284) in the feature-MATH-1284 branch.
I'd appreciate a review by any interested parties. I am particularly concerned to know if the changes represent to much of an API change, even given the target is 4.0. Boring details about the reasoning behind the approach follow. I originally started out intending to keep the Vector?D classes pretty much as-is, dropping the implementation of the Point interface and introducing concrete Point?D classes. In the process of implementing this I learned that the existing code switches between using Vector?D as a Vector and a Point fairly frequently. I started by adding conversion methods but I felt this introduced potential inefficiencies. So I decided to try a different approach. Leveraging the fact that a point and a vector in finite dimensional Euclidean space can both be represented by n-tuples, I created a class for the n-tuples, Cartesian?D (h/t Gilles for the name) which can represent a vector or a point. This approach was much more easily propagated to the remainder of the code and in many places allowed the removal of casts. I also kept the Vector?D classes as an intermediary abstract class in the hope of reducing the burden on a user upgrading from 3.x. Thanks, Ray
