Resolved

Does anyone know of a long distance function that does not: 1. Overflow, 2. Gives pixel perfect distance, 3. Handles distances up to about 200. I have one I'm working with:

function dist(x,y,x2,y2)
 local opp=x-x2
 local adj=y-y2

 return opp/cos(-atan2(opp,adj))
end

However, it has weird instances where it throws up its hands and gives crazy numbers.

Thanks so much for the help!

This is a good one: https://www.lexaloffle.com/bbs/?tid=49827

Last comment in the thread has a version for 3D as well.

Here's mine, not the fastest or smallest, but pretty accurate as all 32 bits of numbers are used for precision of the squares.

function dist(x,y,x2,y2)
 local opp=(x-x2)>>8
 local adj=(y-y2)>>8
 return sqrt(opp*opp+adj*adj)<<8
end

> ? dist(-3000,0,0,4000)
5000
> ? dist(0,0,1,1)
1.4141
> ? sqrt(2)
1.4142

Thank you both! I grabbed @TetraPengwin's because it was faster.