Opened 3 years ago
Closed 3 years ago
#26378 closed defect (fixed)
Bugs in Mass formula for quadratic forms
Reported by: | sbrandhorst | Owned by: | |
---|---|---|---|
Priority: | major | Milestone: | sage-8.4 |
Component: | quadratic forms | Keywords: | |
Cc: | anna, haensch | Merged in: | |
Authors: | Frédéric Chapoton | Reviewers: | Simon Brandhorst |
Report Upstream: | N/A | Work issues: | |
Branch: | 12c4342 (Commits, GitHub, GitLab) | Commit: | 12c434294a7fb4dbe45b424a4069bc9d590e96fa |
Dependencies: | Stopgaps: |
Description
sage: Q = QuadraticForm(Matrix(ZZ,2,[2,1,1,2])) sage: Q.conway_mass() .... TypeError: unable to convert sqrt(1/144) to a rational
The correct result is 1/12.
The method seems to fail in dimension 6 as well for example for the E6 lattice.
Change History (6)
comment:1 Changed 3 years ago by
- Branch set to u/chapoton/26378
- Commit set to 12c434294a7fb4dbe45b424a4069bc9d590e96fa
- Status changed from new to needs_review
comment:2 Changed 3 years ago by
- Status changed from needs_review to positive_review
I tested this against a few thousand lattices of determiants <= 400 in dimensions <= 6 against magma. The answers agree. Thank you so much Frédéric :-).
comment:5 Changed 3 years ago by
- Status changed from needs_work to positive_review
comment:6 Changed 3 years ago by
- Branch changed from u/chapoton/26378 to 12c434294a7fb4dbe45b424a4069bc9d590e96fa
- Resolution set to fixed
- Status changed from positive_review to closed
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here is a fix proposal, not tested on E6
New commits:
fixing conway mass