From: William James <w_a_x_man@...>
Date: 2007-09-04T07:20:10+09:00
Subject: Re: wierd floating point output


Matthias W�chter wrote:
> Stefan Rusterholz schrieb:
> > Matthias W�chter wrote:
> >> What I mean is that any float stored as a IEEE 754 double (64 bit),
> >> like 0.1 with hex notation 0x3FB999999999999A should have a distinct
> >> string representation such that (a==b) == (a.to_s==b.to_s). Note
> >> that the next higher double 0.1+2.0**-56 with hex notation
> >> 0x3FB999999999999B has the same .to_s representation, which is not good.
> > I disagree. As long as you're calculating, you are working with floats
> > anyway, so you have maximum precision. Comparing floats should be done
> > using delta comparison anyway too.
>
> Which, as discussed in the 0.06 thread, is hard to accomplish nevertheless.

Can you give some examples of pairs of floats that are hard
to compare using delta comparison?