[Cado-nfs-discuss] does CADO work for f of degree 2?

Pierrick Gaudry pierrick.gaudry at loria.fr
Thu Oct 23 18:51:46 CEST 2014


Degree 2 is supposed to work.

First, a remark. If I got correctly the tarball, you are trying to use 
# f(x) = x^2+1
# g(x) = x^2+2
Their resultant is 1... I don't know what you expect in the end, but I
bet that it won't be very useful.

Apart from that detail, it seems to be a bug, indeed, because rootRefine
should be called only for polynomials with real roots.

Who knows which algorithm is used to count the number of real roots?

Pierrick

On Thu, Oct 23, 2014 at 05:49:31PM +0200, Francois Morain wrote:
> We are trying to use cado (for DL) with a degree 2 poly. It seems to
> trigger problems, like:
> 2  0x0000000000493864 in rootRefine (r=0x7fffffffd720, p=0x7fffffffd7f0, n=1, 
>     precision=0.0009765625) at /mnt/data/morain/cado-nfs/utils/usp.c:597
> 597   ASSERT_ALWAYS (sa * sb < 0.0);
> (gdb) 
> 
> Can anyone help? Tar gz copied on fcatrel.
> Thanks in advance,
> FM
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