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.

Full log

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Date: Tue, 1 Feb 2011 17:21:49 +0100
From: Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr>
To: 1151@pari.math.u-bordeaux.fr
Subject: Re: Bug#1151: rnfequation(,,1) is broken
Message-ID: <20110201162149.GF3266@yellowpig>
References: <20101218155503.GC9570@yellowpig>
 <20110131235925.GE3266@yellowpig>
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[Message part 1 (text/plain, inline)]
On Tue, Feb 01, 2011 at 12:59:25AM +0100, Bill Allombert wrote:
> 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

The attached patch is probably incorrect, but it allows both 'make test-all' and 
this test
for(i=1,16,print(i);rnfequation(polcyclo(17,y),-x+y^i,1))

to work. Strange...

Bill.

[patch (text/plain, attachment)]

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Bill Allombert <allomber@math.u-bordeaux.fr>. Last modified: Sat Aug 26 17:27:12 2023; Machine Name: pari

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