[Cado-nfs-discuss] "characters" fails with "all dependencies are zero"

Emmanuel Thomé emmanuel.thome at gmail.com
Wed Aug 27 12:04:38 CEST 2014


FYI, I've just changed the default behaviour to be nullspace=left
unless told otherwise for linear algebra over GF(2) (factoring), while
the default is nullspace=right whenever p>2 (this is appropriate for
discrete log). This should remove the risk for failures such as the
one Raphaël encountered.

Best,

E.

On Mon, Aug 4, 2014 at 2:34 PM, Emmanuel Thomé <emmanuel.thome at gmail.com> wrote:
> On Mon, Aug 4, 2014 at 2:06 PM, Raphaël Rigo <ml-cado at syscall.eu> wrote:
>> Unfortunately no I don't have the log :(
>
> Too bad.
>
>> But it appears I forgot to pass nullspace=left. Should I re-run the full
>> linalg step ?
>
> Yes unfortunately. It's really too bad. The default behaviour of
> nullspace=right inherits from the dark ages of this program, when it
> was used to do discrete logs. Now admittedly 99% of the use of this
> code base is with factoring, and we want left nullspace. Of course the
> python code in cado-nfs adds it, but bwc.pl itself does
> nullspace=right unless told otherwise.
>
> E.


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