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Re: [Cado-nfs-discuss] FactorBaseFormat


Chronological Thread 
  • From: Pierrick Gaudry <pierrick.gaudry@loria.fr>
  • To: Pankaj Charpe <charpe.pankajamol@gmail.com>
  • Cc: cado-nfs-discuss@lists.gforge.inria.fr
  • Subject: Re: [Cado-nfs-discuss] FactorBaseFormat
  • Date: Sat, 3 Feb 2018 11:21:24 +0100
  • List-archive: <http://lists.gforge.inria.fr/pipermail/cado-nfs-discuss/>
  • List-id: A discussion list for Cado-NFS <cado-nfs-discuss.lists.gforge.inria.fr>

Hi,

>From an old README file I have somewhere in an old directory:

Factor base file format:
------------------------

An entry is of the form:

q:n1,n2: r1,r2,r3

In the (frequent) case where n1,n2=1,0 this can be abridged with:

q: r1,r2,r3

Here, q is a irreducible or a irreducible power, ri are the corresponding
roots and the contribution that must be subtracted at these positions is
(n1-n2)*degree(p) (assuming smaller powers of this irreducible have
alredy been taken care of). By position, we mean (a,b) such that a -
b*ri = 0 mod q.

The roots ri must be sorted in lexicographical order. If a root ri is
greater or equal to q, it means that this is a projective root:
subtracting q gives a root for the reciprocal polynomial (or
equivalently, (1:(ri-q)) is the projective root).

It is allowed to have several lines with the same q, but there must be
only one line for a given (q,n1,n2) triple.

Hopefully this is still valid in the version you are using.

Regards,
Pierrick

On Sat, Feb 03, 2018 at 01:50:46PM +0530, Pankaj Charpe wrote:
> Hi,
> In factor base construction of cado-nfs we have this entry,
> Factor Base format: q:n1,n2:r1,r2,r3
>
> Can you please explain me what is these n1 and n2 ?. I will be very
> thankful to you.
>
>
> Thanks & Regards
> Pankaj charpe

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