Re: Why is precision(sqrt(0)) < precision(sqrt(1)) ??

Bill Allombert on Mon, 29 Feb 2016 23:46:43 +0100

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Re: Why is precision(sqrt(0)) < precision(sqrt(1)) ??

To: pari-dev@pari.math.u-bordeaux.fr
Subject: Re: Why is precision(sqrt(0)) < precision(sqrt(1)) ??
From: Bill Allombert <Bill.Allombert@math.u-bordeaux.fr>
Date: Mon, 29 Feb 2016 23:46:40 +0100
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On Mon, Feb 29, 2016 at 06:34:30PM +0000, Jacques Gélinas wrote:
> Now, I can understand lowering the precision by half for sqrt(0.), 
> but not for sqrt(0) and then why is is not also done for sqrt(1)  ?

Due to the internal representation of floating point number in PARI,
real 0 do not have a precision in the same sense than non-0 reals.
Instead precision() of a zero is linked to its exponent.

Cheers,
Bill.

References:
- Why is precision(sqrt(0)) < precision(sqrt(1)) ??
  - From: Jacques Gélinas <jacquesg00@hotmail.com>

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