#16743: Extend IsogenyClass_EC to work over number fields
-------------------------------------+-------------------------------------
Reporter: cremona | Owner:
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-6.4
Component: elliptic curves | Resolution:
Keywords: isogeny class | Merged in:
Authors: John Cremona | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/cremona/ticket/16743 | 06d9eb2226151a35bb2d3779e5309f4d066af8ca
Dependencies: #11327, #16764, | Stopgaps:
#16806 |
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Comment (by jdemeyer):
Replying to [comment:10 cremona]:
> Good point, will do. It's clear for prime_ideals() and hnf_cmp() BUT in
the latter case there is already a cmp function for ideals which is very
similar but not good for my purposes: it does not first compare norms,
and it uses the pari_hnf directly. So The simplest thing to do (replace
the existing ideal cmp with mine) may cause a lot of annoying doctest
changes. I'll try and see.
I don't think this should be the default `cmp()` for ideals (it's more
expensive to compute), but it should be function defined in
`rings/number_field/number_field_ideal.py`. And why do you need
{{{
cmp(I.pari_hnf().sage(), J.pari_hnf().sage())
}}}
as opposed to
{{{
cmp(I.pari_hnf(), J.pari_hnf())
}}}
That's not clear to me...
Finally, a Python tip: you can shorten
{{{
t = int(I.norm() - J.norm())
if t:
return cmp(t,0)
return cmp(I.pari_hnf().sage(), J.pari_hnf().sage())
}}}
to
{{{
return cmp(I.norm(), J.norm()) or cmp(I.pari_hnf().sage(),
J.pari_hnf().sage())
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/16743#comment:12>
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