#12356: many missing class number 2 orders in CM j-invariant function over
quadratic fields
-------------------------------------------+--------------------------------
Reporter: cremona | Owner: cremona
Type: defect | Status: needs_review
Priority: critical | Milestone: sage-5.0
Component: elliptic curves | Keywords:
Work_issues: | Upstream: N/A
Reviewer: John Cremona, William Stein | Author: John Cremona,
William Stein
Merged: | Dependencies:
-------------------------------------------+--------------------------------
Old description:
> In sage/schemes/elliptic_curves/cm.py there is a list of imaginary
> quadratic orders with class number 2, introduced in #11220, but it is
> incomplete! Firstly, discriminant -72 is missing since the paper
> referred to omitted it in error; secondly, all 9 such orders whose
> maximal order has class number 1 were omitted by mistake.
>
> The patch adds the missing cases and adjusts the doctests (all for
> Q(sqrt(5)) whose output is now different as more cases are included.
New description:
In sage/schemes/elliptic_curves/cm.py there is a list of imaginary
quadratic orders with class number 2, introduced in #11220, but it is
incomplete! Firstly, discriminant -72 is missing since the paper referred
to omitted it in error; secondly, all 9 such orders whose maximal order
has class number 1 were omitted by mistake.
The original patch (by JEC) adds the missing cases and adjusts the
doctests (all for Q(sqrt(5)) whose output is now different as more cases
are included. The later patches (by WAS) which are independent, do much
much more, handling all class numbers up to 100.
--
Comment(by cremona):
I have started to look at this. The patch applies fine to 4.8 and tests
pass, and seem correct to me. I have quite a few suggestions for making
the code run faster; the question is whether to insist on any of them
now, or put all that into a follow-up ticket, so as not to delay
correcting the *wrong* output which unpatched 4.8 gives.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12356#comment:6>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
