Igor Schein on Mon, 19 Aug 2002 10:30:57 -0400


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Re: bnrL1() bug


On Mon, Aug 19, 2002 at 02:32:32PM +0200, Karim Belabas wrote:
> [Xavier]
> > did I miss the email about the fix for this bug:
> 
> Hi,
> 
>   I have temporarily lost access to my main accounts (ssh misconfigured,
> presumably) and I've done a lot of work with CVS from my home machine, before
> noticing I couldn't announce my changes [ I'm stealing an email account for
> this answer, I saw your message by checking the pari-dev archive. I've no
> access to my mailbox... ].
> 
> Quick list (hopefully, I'll be able to elaborate in a few days):
> 
> * setrand(1);rnfkummer(bnrinit(bnfinit(quadpoly(4760,y)),23,1),matdiagonal([3,1,1])) --> 0
> 
> --> very tough bug. It's the first recorded instance of bnfinit actually
> giving a wrong answer because we cheat on Bach's constant [ should be 12
> log^2 D under GRH, we use 0.3 log^2 D ]. Namely:
> 
> setrand(3); bnfinit(y^4 + 1190*y^2 + 1416100).cyc
>   --> [8, 2, 2, 2] \\ WRONG
> 
> setrand(3); bnfinit(y^4 + 1190*y^2 + 1416100,,[0.6]).cyc,,[0.6]).cyc
>   --> [8, 4, 2] \\ OK
> 
> Trivial to correct [ use correct bound! ], BUT would slow down immensely most
> bnfinit computations ! Certifying the result (bnfcertify) is not an option
> either.

OK, here's another one:

? setrand(4);rnfkummer(bnrinit(bnfinit(quadpoly(5288,y)),9,1),[1,0;0,3]);
  ***   bug in GP (Segmentation Fault), please report
?
 
Is it related to the same bnfinit() problem?

Thanks

Igor