Opened 9 years ago
Closed 6 years ago
#10308 closed defect (fixed)
bug in genus of ideal on 64 bits
Reported by: | lftabera | Owned by: | was |
---|---|---|---|
Priority: | major | Milestone: | sage-5.11 |
Component: | interfaces | Keywords: | genus, Singular, 64bits |
Cc: | Merged in: | sage-5.11.rc0 | |
Authors: | Luis Felipe Tabera Alonso | Reviewers: | Peter Bruin |
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description (last modified by )
The following problem was discovered by Victor Miller in Sage-support
http://groups.google.com/group/sage-support/browse_thread/thread/e30af8c695b6a912
sage: T.<t1,t2,u1,u2> = QQ[] sage: TJ = Ideal([t1^2 + u1^2 - 1,t2^2 + u2^2 - 1, (t1-t2)^2 + (u1-u2)^2 -1]) sage: TJ.genus() 4294967295 sage: TJ.dimension() 1
I can confirm the bug in debian 64bits. Howeber, in debian 32 bits the answer is
sage: TJ.genus() -1
So it seems to be a problem with 232-1 in 32 vs 64 bits.
A simpler example (Ubuntu 64-bit):
sage: R.<x, y, z> = QQ[] sage: C = Curve(x^2 - 2*y^2) sage: C.is_singular() True sage: C.genus() 4294967295
Attachments (1)
Change History (7)
comment:1 Changed 9 years ago by
- Description modified (diff)
Changed 8 years ago by
comment:2 Changed 8 years ago by
- Status changed from new to needs_review
comment:3 Changed 7 years ago by
Please fill in your real name as Author.
comment:4 Changed 7 years ago by
comment:5 Changed 7 years ago by
- Reviewers set to Peter Bruin
- Status changed from needs_review to positive_review
The bug does not appear to be present in 5.11.beta3, the patch applies and the tests that it introduces run correctly. Note that the answer -1
is really the (geometric) genus, not an error code (as one could be led to suspect by the sage-support discussion cited above).
comment:6 Changed 6 years ago by
- Merged in set to sage-5.11.rc0
- Resolution set to fixed
- Status changed from positive_review to closed
It seems to me that the bug is solved in linux 64 bits with newer versions of Sage.
I attach a doctest for the record.