Opened 11 years ago

Closed 11 years ago

#12187 closed defect (fixed)

Bug in is_singular for plane projective curves

Reported by: johanbosman Owned by: AlexGhitza
Priority: major Milestone: sage-4.8
Component: algebraic geometry Keywords:
Cc: cturner Merged in: sage-4.8.alpha6
Authors: Charlie Turner Reviewers: David Loeffler
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Status badges

Description (last modified by cturner) 

sage: P.<X,Y,Z> = GF(2)[]
sage: C = Curve(X^2 + Y*Z)
sage: C.is_singular()
True
sage: C.is_smooth()
True

This happens exactly when the characteristic of the base field divides the degree and the curve is smooth.

Patch 'depends' on #11936 and #11937 to ensure testing passes if Kash is installed.

Attachments (2)

12187.patch​ (1.0 KB) - added by cturner 11 years ago.
Added doctest to show it fixes the bug!
trac_12187.2.patch​ (1.0 KB) - added by davidloeffler 11 years ago.
Apply only this patch -- whitespace changes by reviewer

Download all attachments as: .zip

Change History (8)

comment:1 Changed 11 years ago by cturner

  • Authors set to Charlie Turner
  • Description modified (diff)
  • Status changed from new to needs_review

comment:2 Changed 11 years ago by davidloeffler

  • Status changed from needs_review to needs_work

Can you add a doctest to the patch, showing that the correct output is being produced in examples like the one above?

Changed 11 years ago by cturner

Added doctest to show it fixes the bug!

comment:3 Changed 11 years ago by cturner

  • Status changed from needs_work to needs_review

Changed 11 years ago by davidloeffler

Apply only this patch -- whitespace changes by reviewer

comment:4 Changed 11 years ago by davidloeffler

  • Reviewers set to David Loeffler
  • Status changed from needs_review to positive_review

Hi Charlie,

This looks good but there are a couple of niggling issues with formatting of the docstring: there is a rule that no tab characters should appear in Sage source files, and code blocks in docstrings need to have a double colon and a blank line before them.

I've uploaded a new, corrected patch. Since I've only changed whitespace, I don't think we need another round of checking. All tests pass on selmer.warwick, so this gets a positive review.

comment:5 Changed 11 years ago by cturner

Thank you, David.

comment:6 Changed 11 years ago by jdemeyer

  • Merged in set to sage-4.8.alpha6
  • Resolution set to fixed
  • Status changed from positive_review to closed
Note: See TracTickets for help on using tickets.