Discussion related to cado-nfs

[Paul Zimmermann <Paul.Zimmermann@inria.fr>]

       Dear Hermann,

> Date: Thu, 13 Jul 2023 08:09:45 +0200
> From: hermann@stamm-wilbrandt.de
> 
> On 2023-07-12 15:05, Paul Zimmermann wrote:
> > 
> > Can you reproduce the error if you run manually the following command?
> > 
> > /home/pi/cado-nfs/build/pi400-64/linalg/characters -poly
> > /tmp/cado.z59qan9o/c110.poly -purged /tmp/cado.z59qan9o/c110.purged.gz
> > -index /tmp/cado.z59qan9o/c110.index.gz -heavyblock
> > /tmp/cado.z59qan9o/c110.dense.bin -out /tmp/cado.z59qan9o/c110.kernel
> > -ker /tmp/cado.z59qan9o/c110.bwc/W -lpb0 25 -lpb1 26 -nchar 50 -t 4
> > 
> > And if you replace "-t 4" by "-t 1" (using only one thread)?
> > 
> I did run with "-t 1" and program immediately stopped:
> 
> pi@pi400-64:~/cado-nfs $ 
> /home/pi/cado-nfs/build/pi400-64/linalg/characters -poly 
> /tmp/cado.4x9eajs3/c110.poly -purged /tmp/cado.4x9eajs3/c110.purged.gz 
> -index /tmp/cado.4x9eajs3/c110.index.gz -heavyblock 
> /tmp/cado.4x9eajs3/c110.dense.bin -out /tmp/cado.4x9eajs3/c110.kernel 
> -ker /tmp/cado.4x9eajs3/c110.bwc/W -lpb0 25 -lpb1 26 -nchar 50 -t 1 > 
> /tmp/cado.4x9eajs3/c110.characters.stdout.1 2> 
> /tmp/cado.4x9eajs3/c110.characters.stderr.1
> Aborted
> pi@pi400-64:~/cado-nfs $ wc /tmp/cado.4x9eajs3/c110.characters.stderr.1
>    9  98 866 /tmp/cado.4x9eajs3/c110.characters.stderr.1
> pi@pi400-64:~/cado-nfs $ cat /tmp/cado.4x9eajs3/c110.characters.stderr.1
> /home/pi/cado-nfs/build/pi400-64/linalg/characters.re9cc3be15 -poly 
> /tmp/cado.4x9eajs3/c110.poly -purged /tmp/cado.4x9eajs3/c110.purged.gz 
> -index /tmp/cado.4x9eajs3/c110.index.gz -heavyblock 
> /tmp/cado.4x9eajs3/c110.dense.bin -out /tmp/cado.4x9eajs3/c110.kernel 
> -ker /tmp/cado.4x9eajs3/c110.bwc/W -lpb0 25 -lpb1 26 -nchar 50 -t 1
> # Warning: parameter nratchars is checked by this program but is 
> undocumented.
> Note: total 64 characters, including 14 trivial padding characters
> Reading 1469231 (a,b) pairs from /tmp/cado.4x9eajs3/c110.purged.gz
> Computing 64 characters for 1469231 (a,b) pairs
> Error, Jacobi symbol is 0 for a = 0, b = 0, p = 67108879, r = 28784789
> Please check lpb0/lpb1 are large enough
> terminate called after throwing an instance of 'std::runtime_error'
>    what():  code BUG() : condition res != 0 failed at 
> /home/pi/cado-nfs/linalg/characters.cpp:194
> pi@pi400-64:~/cado-nfs $

ok, good to know the issue is deterministic!

To investigate further, you can try to copy the relevant files to your other
computer (where the factorization succeeded) and run the same command
(with the files generated on the pi400-64).

If it succeeds, the issue might be in the characters command on the pi400-64.

If it fails, it might be the data computed on the pi400-64 are corrupted.

Paul