Float precision and float equality

[r0g]

dbd wrote:
> On Dec 6, 1:12 am, Raymond Hettinger <pyt... at rcn.com> wrote:
>> On Dec 5, 11:42 pm, Tim Roberts <t... at probo.com> wrote:
>>
>>> Raymond Hettinger <pyt... at rcn.com> wrote:
>>>>   if not round(x - y, 6): ...
>>> That's a dangerous suggestion.  It only works if x and y happen to be
>>> roughly in the range of integers.
> .>
> .> Right.  Using abs(x-y) < eps is the way to go.
> .>
> .> Raymond
> 
> This only works when abs(x) and abs(y) are larger that eps, but not
> too much larger.


Okay, I'm confused now... I thought them being larger was entirely the
point. At what point can they become too large? Isn't eps entirely
arbitrary anyway?



> 
> Mark's suggestion is longer, but it works. The downside is it requires
> you to think about the scale and accuracy of your application.
> 


Shouldn't one be doing that in any case??


Roger.