#20774: Basic singularity analysis for algebraic curves
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Reporter: gjorgenson | Owner:
Type: enhancement | Status: needs_work
Priority: minor | Milestone: sage-7.3
Component: algebraic | Resolution:
geometry | Merged in:
Keywords: gsoc2016 | Reviewers: Ben Hutz
Authors: Grayson Jorgenson | Work issues:
Report Upstream: N/A | Commit:
Branch: | e1f15291034546dd48d91284790df481af5aacdf
u/gjorgenson/ticket/20774 | Stopgaps:
Dependencies: |
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Changes (by bhutz):
* status: needs_review => needs_work
* reviewer: => Ben Hutz
Comment:
some comments in no particular order
- the values I've checked agree with Magma.
- I would rather see a while loop than a for/break since you are using the
loop variable later when you are getting an appropriate affine patch
- examples are all QQ or number field. I'd like to see some other fields
(assuming they work)
- in multiplicity: why don't you change ring first to get the ordering,
and then use R.ideal to create the ideal. That way you only have to
change_ring once instead of twice.
- OUTPUT: an integer. You don't have to make a list when it is a simple
output
- multiplicity = 0: do you really want to allow this? I think returning an
error that the point is not on the curve may be more intuitive. If you
change it: in tangents: if r < 1 isn't needed. Either way, this should be
described in the doc
- in is_ordinary: OUTPUT: Boolean. You should document that an error is
returned for a non-singular point
- in singular_points: I think putting F=F is better than adding the 0 as
the first parameter.
- do you want to add C.singular_subscheme()?
- I see many places you are restricting to fields. Should there be a field
subclass?
- Things like Q.is_ordinary_singularity(), Q.tangents(), Q.multiplicity()
don't work when Q is the curve point.
- Q.is_singular() and C.is_singular(Q) would be nice to have.
--
Ticket URL: <http://trac.sagemath.org/ticket/20774#comment:5>
Sage <http://www.sagemath.org>
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