PARI/GP Bug report logs - #1151
rnfequation(,,1) is broken

Package: pari; Maintainer for pari is Aurel Page <aurel.page@normalesup.org>; Source for pari is src:pari.

Reported by: Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr>

Date: Sat, 18 Dec 2010 16:03:01 UTC

Severity: normal

Done: Karim Belabas <Karim.Belabas@math.u-bordeaux1.fr>

Bug is archived. No further changes may be made.

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Subject: Bug#1151: rnfequation(,,1) is broken
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Date: Tue, 1 Feb 2011 00:59:25 +0100
From: Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr>
To: 1151@pari.math.u-bordeaux.fr
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On Sat, Dec 18, 2010 at 04:55:03PM +0100, Bill Allombert wrote:
> Package: pari
> Version: 2.4.3, 2.3.5
> 
> Hello Karim,
> This issue was reported on the pari-users list
> <http://pari.math.u-bordeaux.fr/archives/pari-users-1012/msg00004.html>.
> I report it for reference.
> 
> ? f = (y^17-1)/(y-1);
> ? g = Mod(1,f)*x+Mod(y^6,f);
> ? rnfequation(f,g,1);
>   ***   at top-level: rnfequation(f,g,1)
>   ***                 ^------------------
>   *** rnfequation: the PARI stack overflows !

Well, according to my calculation the correct LERS is:
(-x^4 + x^3 - x^2)*y + (-x^7 + x^6 - x^5)

Furthermore, the values returned by Flx_resultant_all for x=2 are 144 times too large.
For x=3 the values are random but the quotient H0/H1 seems correct

Cheers,
Bill.

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Bill Allombert <allomber@math.u-bordeaux.fr>. Last modified: Sat Aug 26 17:27:11 2023; Machine Name: pari

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