Opened 11 years ago

Closed 6 years ago

#5392 closed defect (fixed)

relative number field subfield method -- unclear documentation

Reported by: dmharvey Owned by: davidloeffler
Priority: major Milestone: sage-5.11
Component: number fields Keywords: sd51
Cc: Merged in: sage-5.11.rc0
Authors: Alejandro Argaez Reviewers: Michiel Kosters
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Description

Consider

sage: R.<a> = NumberField(x^4 - 2*x^2 - 1)
sage: S.<i> = R.extension(x^2 + 1)
sage: S.subfield(a + i/a)

The S.subfield method documentation says that it constructs QQ(alpha), but this is false, I think it constructs R(alpha). In the above example, S.subfield(a + i/a) returns a number field of degree 8 over Q, whereas a + i/a has degree 4 over QQ (the minimal polynomial is x^4 - 4x^2 + 8).

Attachments (2)

trac_5392.patch (2.0 KB) - added by ArgaezG 6 years ago.
patch against sage 5.10
trac_5392_subfield_review.patch (1.1 KB) - added by mkosters 6 years ago.

Download all attachments as: .zip

Change History (12)

comment:1 Changed 11 years ago by mabshoff

  • Milestone set to sage-3.4.1

comment:2 Changed 10 years ago by davidloeffler

  • Component changed from number theory to number fields
  • Owner changed from was to davidloeffler

Changed 6 years ago by ArgaezG

patch against sage 5.10

comment:3 Changed 6 years ago by ArgaezG

  • Authors set to Alejandro Argaez
  • Report Upstream set to N/A
  • Status changed from new to needs_review

comment:4 Changed 6 years ago by mkosters

  • Keywords sd51 added

comment:5 Changed 6 years ago by ArgaezG

  • Reviewers set to Michiel Kosters
  • Status changed from needs_review to positive_review

I happy with changes suggested by Michiel, and he is happy with mine.

comment:6 Changed 6 years ago by mkosters

Apply trac_5392_subfield_review.patch after trac_5392.patch​

comment:7 Changed 6 years ago by jdemeyer

  • Status changed from positive_review to needs_work

The reviewer patch needs a proper commit message, use hg qrefresh -e for this.

Changed 6 years ago by mkosters

comment:8 follow-up: Changed 6 years ago by mkosters

@jdemeyer: is it correct now?

comment:9 in reply to: ↑ 8 Changed 6 years ago by mstreng

  • Status changed from needs_work to positive_review

Replying to mkosters:

@jdemeyer: is it correct now?

It has a proper commit message now. So assuming this is the same patch, I'll put this to positive review again.

comment:10 Changed 6 years ago by jdemeyer

  • Merged in set to sage-5.11.rc0
  • Resolution set to fixed
  • Status changed from positive_review to closed
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