Ryan Curtin

Oh, sounds good, no worries (and no hurry). Don't forget to add a test for the new gain function :+1: I don't think it should be a part of this...

Yeah, the way to do it (I did it in 2015 but for some reason never opened a PR because it needed tuning that I never had the time for)...

Have you checked whether the distance computation itself is parallelized? If it's not, simply parallelizing that instead might give significantly more speedup. (Note that mlpack doesn't require OpenMP to be...

The reason I am hammering so hard (now for I believe the fifth time) about the distance calculation is because it is not always the right thing to simply observe...

It's not possible to directly compare mlpack's and Armadillo's k-means implementations without further digging. They will run for different numbers of iterations, to different tolerance measures, etc., etc... the way...

I do think that we need to get to the bottom of why `arma::norm()` isn't giving good performance in our case, but for the sake of getting something merged, I...

There are a lot of changes here that aren't actually functional changes---do you mind going through and reducing the changes to only the actual functionality changes? Thanks :+1:

Thanks for the hard work @MarkFischinger! I opened https://github.com/mlpack/mlpack/issues/3789 to follow up on the `EuclideanDistance` efficiency issue. We can continue that there. I think I need to fix the documentation...

Sorry this one took so long, I think #3752 should be a fix.

@shrit this is awesome! To me the primary question here is one of organization: how should we structure the embedded documentation? I think it has two components: * tutorials *...