How do you calculate %xHKO?

Yeah, I tested the method in Lua (which supposedly runs pretty fast, as far as interpreted scripting languages go) and found that it was kinda really loopy and inefficient, but couldn't come up with a better way, and so I sort of gave up on trying to get exact answers. What you could do is round the damage down by 10's or 100's as the range gets larger, or just calculate in units of 1/100th-of-damage-range or something like that. But in that case I prefer the calculus approach. Heheh.