Opened 4 years ago
Closed 4 years ago
#24453 closed defect (fixed)
narrow_class_group: bug report
Reported by:  kimball  Owned by:  

Priority:  major  Milestone:  sage8.2 
Component:  number fields  Keywords:  narrow class group, quadratic field 
Cc:  Merged in:  
Authors:  Frédéric Chapoton  Reviewers:  Vincent Delecroix 
Report Upstream:  N/A  Work issues:  
Branch:  13f3864 (Commits, GitHub, GitLab)  Commit:  13f3864c0c0932cc2ee24bd49f38fdcb4207d79f 
Dependencies:  Stopgaps: 
Description
The narrow_class_group function does not even work for some simple real quadratic fields. Specifically, while it works for Q(sqrt(2)), it does not for Q(sqrt(3)) (I have not tried other number fields). See snippet below.
sage: version() 'SageMath version 8.1, Release Date: 20171207' sage: F.<a> = QuadraticField(2) sage: F.narrow_class_group() Trivial Abelian group sage: F.<a> = QuadraticField(3) sage: F.narrow_class_group() File "<string>", line 1 [2, [2], [[0, 1]~]] ^ SyntaxError: invalid syntax sage: NumberField(x^23,'a').narrow_class_group() File "<string>", line 1 [2, [2], [[0, 1]~]] ^ SyntaxError: invalid syntax
If it matters, I was using a prebuilt Mac binary.
Change History (6)
comment:1 Changed 4 years ago by
comment:2 Changed 4 years ago by
 Branch set to u/chapoton/24453
 Commit set to 13f3864c0c0932cc2ee24bd49f38fdcb4207d79f
 Status changed from new to needs_review
New commits:
13f3864  trac 24453 fix narrow class field

comment:3 Changed 4 years ago by
Why did you make it a cached method?
comment:4 Changed 4 years ago by
oh, well, I thought it would be a good idea to replace the custom cache by the usual decorator..
comment:5 Changed 4 years ago by
 Reviewers set to Vincent Delecroix
 Status changed from needs_review to positive_review
Oh! I missed the old cache.
comment:6 Changed 4 years ago by
 Branch changed from u/chapoton/24453 to 13f3864c0c0932cc2ee24bd49f38fdcb4207d79f
 Resolution set to fixed
 Status changed from positive_review to closed
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Indeed, there is maybe something strange..