OK. I made some progress but am still kind of bewildered. I now think the convergent square root curve is used (in the vote operation itself, I didn't notice at first that it picked the "curation" curve since I was so used to seeing the other curve in the rewards code). I think it sets the curation-payout-weight based on the delta between the new convergent-sqrt of rshares and the old convergent-sqrt of rshares. But my numbers aren't lining up with the actual payouts on the post. I'm wondering if maybe the data structure my script is getting for the votes isn't in order.