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Bill Allombert on Thu, 22 Feb 2024 11:44:02 +0100
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Re: Numerical instability in extracting base B digits of the fractional part of real
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- To: pari-dev@pari.math.u-bordeaux.fr
- Subject: Re: Numerical instability in extracting base B digits of the fractional part of real
- From: Bill Allombert <Bill.Allombert@math.u-bordeaux.fr>
- Date: Thu, 22 Feb 2024 11:43:56 +0100
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On Thu, Feb 22, 2024 at 09:13:31AM +0200, Georgi Guninski wrote:
> Some observations:
> 1. With precision 100 I get correct result.
Sure, this is due to base 2 to base 10 conversion.
33/100 cannot be represented exactly in base 2,
so depending of the precision it will be represented either as
33/100 + epsilon
or 33/100 - epsilon
in the first case, you will get 0,3,3,0,0,0,0,...
and in the second you will get 0,3,2,9,9,9,9,9
But you can obtain the correct result by using 33/100 instead of .33
Cheers,
Bill.