[Haskell-cafe] smallest double eps

Lennart Augustsson lennart at augustsson.net
Sat Sep 30 04:19:50 EDT 2006

Hang on, hang on, now I'm getting confused.

First you asked for the smallest (positive) x such that
    1+x /= x
which is around x=4.5e15.
Then Joachim wondered if you wanted
    1+x /= 1
which is around x=2.2e-16.
But not you claim to be looking for the smallest positive number that  
a Double can represent.  Which is a totally different beast.  The  
smallest possible Double depends on if you want to accept  
denormalized numbers or not.  If you don't, then it's about x=4.5e-308.

Now what is the number you are looking for?

	-- Lennart

On Sep 29, 2006, at 22:02 , Tamas K Papp wrote:

> On Fri, Sep 29, 2006 at 06:53:35PM -0700, Chad Scherrer wrote:
>> Tamas,
>> You might want to read Joachim's post more carefully - he's trying to
>> help you, and I think he makes a good point.
> Chad,
> If his point is that there is no smallest positive number, then I
> think I understand it, thanks.  I should have said that I was looking
> for the smallest positive number Double can represent, but thought
> that was clear from the context.
> If this is not his point, I'd really appreciate an explanation.
> Thanks,
> Tamas
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