Re: NSKeyedArchiver and NSPoints
Re: NSKeyedArchiver and NSPoints
- Subject: Re: NSKeyedArchiver and NSPoints
- From: Michael Ash <email@hidden>
- Date: Thu, 29 Apr 2010 19:33:48 -0400
On Thu, Apr 29, 2010 at 12:55 AM, Quincey Morris
<email@hidden> wrote:
> On Apr 28, 2010, at 20:49, Michael Ash wrote:
>
>> Actually, while there are finite decimal numbers with no finite binary
>> representation, the reverse is not true. Every binary number can be
>> represented by a finite number of decimal digits. I believe this is
>> because 2 is a factor of 10. To prove it to yourself, just take
>> successive negative powers of two and notice how you never get a
>> repeating decimal. The fractional part of a binary float is just a sum
>> of various negative powers of two, and if the individual components
>> are finite, the result must be as well.
>
> I'm pretty sure that what I said was 100% accurate this morning, but that the fundamental mathematical laws of the universe have changed since then and now I'm wrong. You're right.
Understandable. If only the universe would sit still for a moment,
maybe I could finally get a handle on it.
>>> Plus, you'd have to expect that encoding doubles would require, in the worst case, at least 309 significant digits, which is a much longer string than I want in my archive.
>>
>> I think you've flipped your math around somewhere here.
>
> Yup, I noticed earlier I'd gone overboard with this, and got myself mixed up with the maximum exponent.
>
> Good thing I published a disclaimer earlier, or otherwise I've have to feel embarrassed now.
Hey, as consequences for bad math go, this is pretty light.
Mike
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