id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,merged,author,reviewer,upstream,work_issues,branch,commit,dependencies,stopgaps
20391,count_points breaks on even-degree hyperelliptic curves,kedlaya,,"The following is currently broken:
{{{
sage: x = polygen(GF(4099))
sage: H = HyperellipticCurve(x^6 + x + 1)
sage: H.count_points(1)
...
ValueError: Q must be a monic polynomial of odd degree >= 3
}}}
The problem is that ultimately this is trying to call hypellfrob, which is only implemented for odd degree polynomials. One can patch around this using either PARI's hyperellcharpoly or the naive point counting code.
In the longer term, some more intelligent switching needs to be implemented for this method, as well as the related zeta_function and zeta_series methods; these do not all optimize the same way. See #965, #16931, #18916, #20309 for related discussions.",defect,closed,major,sage-7.5,algebraic geometry,fixed,"hyperelliptic curve, number of points",cremona,,Kiran Kedlaya,Jean-Pierre Flori,N/A,,dabfdd8c05077107b64d4c038fe20f6609f893c3,dabfdd8c05077107b64d4c038fe20f6609f893c3,#18916,