From: Logan Capaldo <logancapaldo@...>
Date: 2007-09-01T08:16:42+09:00
Subject: Re: 0.06 == 0.06 returns false in Ruby?

On 8/31/07, Kyle Schmitt <kyleaschmitt@gmail.com> wrote:
> On 8/30/07, doug meyer <doug.meyer@sigeps.org> wrote:
> > There is also a class called BigDecimal (or something like that) if
> > you want to have really accurate numbers and no floating-point errors.
>
> A warning on things like BigDecimal.
> Unless I'm mistaken it's still stored in twos compliment, which means
> you'll still end up with the same sort of floating point problems
> (albeit further down), and the same numbers that you can't express
> exactly with a normal float, can't be expressed exactly with a
> BigDecimal.
>
Um, 2's compliment is not a cause of floating point error. IEEE
floating point numbers do not use two's complement, they have a sign
bit. Two's complement is just a way of encoding the sign of a value.
> You'd think some fixed point math libraries would help, but be
> careful, because many of those _also_ store in twos compliment.
>
Again, the use of two's complement or lack thereof is totally irrelevant.
> --Kyle
>
>