Opened 6 years ago

Closed 6 years ago

#16903 closed defect (fixed)

bugfix for database_cremona_ellcurve optional spkg

Reported by: cremona Owned by:
Priority: minor Milestone: sage-6.4
Component: packages: optional Keywords: elliptic curve database
Cc: Merged in:
Authors: John Cremona Reviewers: Volker Braun
Report Upstream: N/A Work issues:
Branch: b9125a4 (Commits) Commit: b9125a4f258a97358b5aca69f2d44f4ee63b835e
Dependencies: Stopgaps:

Description (last modified by cremona)

The following (requires optional database_cremona_ellcurve) reveals a problem:

sage: CremonaDatabase().largest_conductor()
sage: E = EllipticCurve([0,1,0,-141083,-20443787])
sage: E.conductor()
sage: E.label()
RuntimeError: Cremona label not known for Elliptic Curve defined by y^2 = x^3 + x^2 - 141083*x - 20443787 over Rational Field.
sage: E = EllipticCurve([0,-1,0,-16,421])
sage: E.conductor()
sage: E.label()
RuntimeError: Cremona label not known for Elliptic Curve defined by y^2 = x^3 - x^2 - 16*x + 421 over Rational Field.

which was reported by Benjamin Matschke and Rafael von Kanel on 2014-08-28. The database files are missing all curves with conductors in the ranges 246400-246499 and 252800-252899, in total 1455 elliptic curves in 962 isogeny classes. I am making an update to the database_cremona_ellcurve option spkg.

New tarball :

Change History (6)

comment:1 Changed 6 years ago by cremona

In preparing the new database file (the file cremona.db in SAGE_ROOT/local/share/cremona) which is done using the command on the updated tar file I find that I have to change that script, because I have "tidied up" the file structure in the tarball so that the data files are in subdirectories.

It seems sensible to make those changes in the same branch as the ones for the new spkg (updating package version and checksums).

If the new spkg works OK I think that will be good evidence for the new cremona.db file being good.

comment:2 Changed 6 years ago by cremona

  • Description modified (diff)

comment:3 Changed 6 years ago by cremona

  • Branch set to u/cremona/ticket/16903
  • Commit set to b9125a4f258a97358b5aca69f2d44f4ee63b835e
  • Status changed from new to needs_review

After installing the new version:

sage: CremonaDatabase().number_of_curves()
sage: CremonaDatabase().number_of_isogeny_classes()


sage: E = EllipticCurve([0,1,0,-141083,-20443787])
sage: E.label()
sage: E = EllipticCurve([0,-1,0,-16,421])
sage: E.label()

New commits:

b9125a4#16903: new version of database_cremona_ellcurve optional spkg

comment:4 Changed 6 years ago by vbraun

  • Reviewers set to Volker Braun
  • Status changed from needs_review to positive_review


comment:5 Changed 6 years ago by cremona

Wow, I am impressed with the speed of that review! Thanks,


comment:6 Changed 6 years ago by vbraun

  • Branch changed from u/cremona/ticket/16903 to b9125a4f258a97358b5aca69f2d44f4ee63b835e
  • Resolution set to fixed
  • Status changed from positive_review to closed
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