On Mon, 13 Oct 2003, Bill Stephenson wrote:
> I've got a script that takes numbers similar to those below and then rounds
> them and adds them together using code similar to what is below.
[snip]
> The code above prints this result (system 10.1.5, perl 5.6.0):
>
> 1.66, 1.75
>
> But shouldn't it be:
>
> 1.66, 1.76
>
> or:
>
> 1.65, 1.75
>
> I'm no math wizard, so if someone could please take the time and tell what
> I'm missing here I would very much appreciate it!
Welcome to the wonderful world of inexact representations.
You're getting bitten by some fundamental issues with floating point
representations of numbers. Floating point fractions are base 2, so they
can't properly represent anything that's not base 2. (And, since our
decimal fractions are base 10, that can be a lot of 'em)
There's more explanation in the perl faq, along with some workarounds.
Dan
