Opened 13 years ago
Closed 13 years ago
#2197 closed defect (duplicate)
Elliptic Curve quadratic/quartic/sextic twists: unhelpful error message when D=0
Reported by: | cremona | Owned by: | was |
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Priority: | major | Milestone: | sage-duplicate/invalid/wontfix |
Component: | algebraic geometry | Keywords: | |
Cc: | Merged in: | ||
Authors: | Reviewers: | ||
Report Upstream: | Work issues: | ||
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description
The code for quadratic, quartic and sextic twists of elliptic curves does not check that the twisting parameter is nonzero, and hence fail when a singular curve tries to be constructed. Instead we output a helpful message.
Note that in characteristic 2, the quadratic twist by 0 is allowed (but gives back the same curve), just as twisting by 1 in odd characteristic.
The patch provided also enhances the Hasse_bounds function (which should probably be put somewhere other than ell_generic.py).
Change History (2)
comment:1 Changed 13 years ago by
- Milestone set to sage-2.10.2
comment:2 Changed 13 years ago by
- Milestone changed from sage-2.10.2 to sage-duplicate/invalid
- Resolution set to duplicate
- Status changed from new to closed
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This is a duplicate of #2196.