Re: What´s the algorithm that compresses a 20 digit big int, into 8 bytes ?

From: paul c <toledobythesea_at_oohay.ac>
Date: Fri, 09 Apr 2010 17:27:06 GMT
Message-ID: <KrJvn.1317$Z6.704_at_edtnps82>


Bob Badour wrote:
> paul c wrote:
>

>> Rafael Anschau wrote:
>>
>>> On Apr 9, 11:45 am, Bob Badour <bbad..._at_pei.sympatico.ca> wrote:
>>>
>>>> If it support the full 20 decimal digit range, no algorithm will fit it
>>>> into 64 bits so choosing a different algorithm will achieve nothing.
>>>
>>> Any proof of that, or is it just another hypothesis ? My intuition
>>> tells me this is true, but I would like to see a proof of that.
>>>
>> Open up your calculator and look at the result of 2 to the power of 
>> 63.  I get 9,223,372,036,854,775,808.  Only nineteen digits.

>
> But in my calculator (2^64)-1 gives 18,446,744,073,709,551,615 which has
> 20 digits.

I'm sure it does. I didn't bother with complement nuances because the number of digits proves the point. Received on Fri Apr 09 2010 - 19:27:06 CEST

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