#7907 closed defect (fixed)
Bug in characteristic 2 isogenies of degree >3
Reported by: | cremona | Owned by: | cremona |
---|---|---|---|
Priority: | major | Milestone: | sage-4.3.1 |
Component: | elliptic curves | Keywords: | isogeny |
Cc: | wuthrich, shumow | Merged in: | sage-4.3.1.alpha2 |
Authors: | John Cremona | Reviewers: | Christian Wuthrich |
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description (last modified by )
The method __compute_omega_general()
in ell_curve_isogeny.py contains
for j in xrange(0,n-1): psi_prpr = psi_prpr + \ binomial(j+2,2)*psi_coeffs[(j+2)]*cur_x_pow cur_x_pow = x*cur_x_pow
where the degree of the isogeny is 2*n+1. In degree 3 (the only case doctested) n=1 and the loop is empty. Otherwise there is a run-time error since the name "binomial" has not been imported.
This will be simple to patch, but of course as this indicated that higher degree isogenies in char.2 have not been tested, other issues might arise.
Patch up soon.
Attachments (2)
Change History (9)
comment:1 Changed 10 years ago by
- Description modified (diff)
comment:2 Changed 10 years ago by
comment:3 Changed 10 years ago by
- Status changed from new to needs_review
comment:4 Changed 10 years ago by
- Cc wuthrich shumow added
comment:5 Changed 10 years ago by
- Status changed from needs_review to positive_review
fine. it passes all tests.
comment:6 Changed 10 years ago by
- Merged in set to 4.3.1.alpha2
- Resolution set to fixed
- Reviewers set to Christian Wuthrich
- Status changed from positive_review to closed
comment:7 Changed 10 years ago by
- Merged in changed from 4.3.1.alpha2 to sage-4.3.1.alpha2
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Here's an example of the failure which will be put into a doctest in the patch.
Before:
After: