[R] Efficient distance calculation on big matrix

[Stefan Evert]

> It so happens I have been looking at very similar changes, as well as
> adding multi-threading support for dist(); these should make it into
> R-devel later this summer.

That's good to hear!  I was thinking about giving OpenMP a try in my package, but am not sure whether it's worth the overhead and risk of compatibility problems.

Are there any plans to expand dist() to calculate "cross-distances" between two different sets of vectors?  If so, I'd be able to do away with my custom implementation once your improved dist() has made it into a stable R release.  (I need cross-distances for nearest neighbour search in large sets of vectors.)

Best,
Stefan