infinite (fractional) precision

Ashley Yakeley
Thu, 10 Oct 2002 02:25:59 -0700

At 2002-10-10 01:29, Ketil Z. Malde wrote:

>I realize it's probably far from trivial, e.g. comparing two equal
>numbers could easily not terminate, and memory exhaustion would
>probably arise in many other cases.

I considered doing something very like this for real (computable) 
numbers, but because I couldn't properly make the type an instance of Eq, 
I left it. Actually it was worse than that. Suppose I'm adding two 
numbers, both of which are actually 1, but I don't know that:

 1.000000000.... +

The trouble is, as far as I know with a finite number of digits, the 
answer might be


or it might be

 2.0000000000013565 I can't actually generate any digits at all. So I can't even make 
the type an instance of my Additive class. Not very useful...

Ashley Yakeley, Seattle WA