Not when I factor out the current time (as a global constant) to get the static sort key above.

By factoring out the current time, items exponentially decay without us having to update them (new stuff is exponentially fresher is how I think about it).

Wouldn't you be taking the exponent of a negative, so it would only shrink down to zero at some point?

SimpleStacker

I think I've got a static (time invariant) sort key for this. The exponent is huge and I can't store a log value because negative zap amounts are a thing. I have to store the time of the last zap along with the moving sum in order to incrementally update the sum right, but it isn't that bad (especially for how cool it is).

The SN home page is an auction

Scoresby

$$
\text{Rank}_i = \sum_{j} \text{zap\_amount}_{ij}\, e^{\lambda\, \text{zap\_time}_{ij}}\,\,\,\, \text{ where }\,\,\,\, \lambda = \frac{\ln 2}{4h}
$$

I think I've got a static (time invariant) sort key for this. The exponent is huge and I can't store a log value because negative zap amounts are a thing. I have to store the time of the last zap along with the moving sum in order to incrementally update the sum right, but it isn't that bad (especially for how cool it is).