Opened 12 years ago

Closed 11 years ago

#10177 closed defect (fixed)

Gamma0 equivalence function for number field cusps returns wrong transformation matrix

Reported by: mtaranes Owned by: craigcitro
Priority: major Milestone: sage-4.6.1
Component: modular forms Keywords: number field cusps
Cc: cremona Merged in: sage-4.6.1.rc0
Authors: Maite Aranes Reviewers: David Loeffler
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

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Description

The transformation matrix returned by 'is_Gamma0_equivalent' for number field cusps is not in Gamma0(N). My fault (this is even wrong in the example I wrote for the documentation, sorry...):

  sage: k.<a> = NumberField(x^2 + 5)
  sage: N = k.ideal(3)
  sage: alpha = NFCusp(k, 3, a + 1)
  sage: beta = NFCusp(k, 2, a - 3)
  sage: alpha.is_Gamma0_equivalent(beta, N, Transformation=True)
  (True, [2*a - 4, -3*a - 4, -5*a + 2, 3*a + 13])

The matrix is not in Gamma0(3)!

It's not difficult to compute the right matrix. I'll be happy to write a patch in a few weeks (after I submit my thesis).

Attachments (1)

trac_10177_transf_matrix_fix.patch (2.1 KB) - added by mtaranes 11 years ago.

Download all attachments as: .zip

Change History (6)

Changed 11 years ago by mtaranes

comment:1 Changed 11 years ago by mtaranes

  • Status changed from new to needs_review

Here is a patch, based on Sage 4.6.

comment:2 follow-up: Changed 11 years ago by davidloeffler

  • Authors set to Maite Aranes
  • Milestone set to sage-4.6.2
  • Reviewers set to David Loeffler
  • Status changed from needs_review to positive_review

Looks fine to me, and all doctests in sage/modular pass. (I set the milestone to 4.6.2, as 4.6.1 is in feature freeze, I believe).

comment:3 in reply to: ↑ 2 Changed 11 years ago by cremona

Replying to davidloeffler:

Looks fine to me, and all doctests in sage/modular pass. (I set the milestone to 4.6.2, as 4.6.1 is in feature freeze, I believe).

Thanks, David -- it would quite nice to get this in before Maite's viva (Jan 27th)!

comment:4 Changed 11 years ago by jdemeyer

  • Milestone changed from sage-4.6.2 to sage-4.6.1

Milestone set back to 4.6.1 by special request from John Cremona.

comment:5 Changed 11 years ago by jdemeyer

  • Merged in set to sage-4.6.1.rc0
  • Resolution set to fixed
  • Status changed from positive_review to closed
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