I'm not saying you should read all this, but this issue is a well
known fact about floating point math in programing languages, and it's
present in lots of languages.

http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html

Gedece

On Fri, Mar 30, 2012 at 10:04, Steven Owens <lists / ruby-forum.com> wrote:
> Hello guys,
>
> I'm just starting out with the Ruby language, and appear to either be
> doinf something wrong, or have run into a rather basic math bug.  > running "irb", simple math additions seem to sometimes have weird
> results.   >
> 1.9.3-p125 :022 > 120.02+82
> > 202.01999999999998
>
> but then
>
> 1.9.3-p125 :023 > 120.03+82
> > 202.03
>
> This anomoly seems to be repeatable on a friends box as well.  
> I was onyl able to trigger this with a 3 digit number starting with a 1,
> with .08 after, plus a 2 digit number.  > combinations have also had this kind of issue.
>
> 1.9.3-p125 :030 > 120.009+82
> > 202.00900000000001
>
> Here is a few more examples
>
> 1.9.3-p125 :021 > 120.01+82
> > 202.01
> 1.9.3-p125 :022 > 120.02+82
> > 202.01999999999998
> 1.9.3-p125 :023 > 120.03+82
> > 202.03
> 1.9.3-p125 :024 > 120.04+82
> > 202.04000000000002
> 1.9.3-p125 :025 > 120.05+82
> > 202.05
> 1.9.3-p125 :026 > 120.06+82
> > 202.06
> 1.9.3-p125 :027 > 120.07+82
> > 202.07
> 1.9.3-p125 :028 > 120.08+82
> > 202.07999999999998
> 1.9.3-p125 :029 > 120.09+82
> > 202.09
>
> Now since I'm quite new to this, I realize that this could of course be
> something I'm doing wrong, but obviously, since I'm tyring to learn, I'd
> like to know why I'm getting these results.   >
> --
> Posted via http://www.ruby-forum.com/.
>