No problem at all. I almost went crazy because trusted you :) so you can imagine a storm in my mind :) Good we're clear. 

Back to the subject: I actually have started with simple vectors (actually, simply []float64 arrays), however since your implementation relied on Matrices, I remade it.

Do we really want an overhead of Matrices here? Or can we go ahead and use []float64?

Here (old branch): https://github.com/sjwhitworth/golearn/blob/feature/ifesdjeen/distances/distance/distance.go

So basically this way we always know we operate only vectors, never touching any matrices. 

Think of it.