Also, some quick measurements indicate that the correct summation is approximately 20&times; slower than naive summation :( (for the above data test) however, the `~[]` implementation is not at all fast (and creates a lot of code), so I think that that is the main culprit; that is, we'll likely magically see a dramatic speed-up if/when `~[]` gets replaced by a faster implementation.

That said, the performance of this functions is now data dependent, so, e.g. if I take `1e60` &rarr; `1e6` and `1e30` &rarr; `1e3` in the above example, then the partials sums vector is not used as much (i.e. it has length 1 always, since these numbers are all close-enough to each other to not have much numerical error) and we're only 10&times; slower than naive summation.