From: Alex LeDonne <aledonne.listmail@...>
Date: 2007-09-05T05:42:01+09:00
Subject: Re: wierd floating point output

On 9/4/07, Matthias W�chter <matthias@waechter.wiz.at> wrote:
> Right, floats are approximations of decimals. But they stand for
> theirself. A float or double is a precise representation of a
> base-2-encoded floating point. If I ask for a float for "0.25" I
> expect it to be _precise_, not an approximation. That is part of
> IEEE 754. Certainly, For "0.1" it is an approximation, but the float
> (say, double) representation of 0.1, which is only an approximation
> for 0.1, converted back to decimal is _precisely_
> "0.1000000000000000055511151231257827021181583404541015625", period.
> Please accept that fact.
>
> Now that we know the precise value of the float back in decimal, we
> can make three cases:
...
> 2. I am not interested in the high precision of converting double
> back to a decimal string representation, but I am interested in a
> string representation that allows me, like for any other object, to
> distinguish two different binary float values.

It is not true that "for any other object" a to_s call provides a
string representation which will allow disambiguation of all distinct
values. That's not what to_s is for - to_s is about what to use in the
default case when a string representation is called for. I personally
would be put off if 0.1.to_s returned anything but "0.1" by default.

> 3. I am not interested in high-precision output as I know that
> arbitrary decimal values are handled using approximations after all,
> and I don't want to be bothered with this level of detail.

to_s is for just this sort of default case, which covers the vast,
vast majority of use of the language.

If you want to start talking about Float#inspect, you may find more
listeners. :)

-A