#21097 closed defect (fixed)

incorrect parent for dynatomic polynomial

Reported by: mmanes Owned by:
Priority: minor Milestone: sage-7.4
Component: algebraic geometry Keywords:
Cc: Merged in:
Authors: Michelle Manes, Ben Hutz Reviewers: Patrick Ingram, Michelle Manes
Report Upstream: N/A Work issues:
Branch: 93b2e22 (Commits) Commit: 93b2e226ae50ff61f5592b26abdbb19898da3682
Dependencies: Stopgaps:

Description

dynatomic_polynomial returns polynomial over integers (instead of rationals) when called on rational function over QQ for fixed point polynomial

P.<x, y> = ProjectiveSpace(QQ, 1)
H = End(P)
f = H([x^3-y^3*2, y^3])
dyna = f.dynatomic_polynomial([0,1])
dyna.parent()

Change History (11)

comment:1 Changed 14 months ago by mmanes

  • Branch set to u/mmanes/incorrect_parent_for_dynatomic_polynomial

comment:2 Changed 14 months ago by mmanes

  • Authors set to Michelle Manes
  • Commit set to 36ff748509afe07b949c0ba69cf378204867b49c
  • Status changed from new to needs_review

New commits:

36ff74821097: fix incorrect parent for dynatomic polynomial

comment:3 Changed 14 months ago by pingram

  • Status changed from needs_review to needs_work

The 0th dynatomic polynomial should be returning as 0, not the same as dynatomic_polynomial(1)

P.<x, y> = ProjectiveSpace(QQ, 1)
H = End(P)
f = H([x^2+5*y^2, y^2])
print f.dynatomic_polynomial([0, 0])
print f.dynatomic_polynomial(0)

comment:4 Changed 14 months ago by bhutz

  • Branch changed from u/mmanes/incorrect_parent_for_dynatomic_polynomial to u/bhutz/incorrect_parent_for_dynatomic_polynomial

comment:5 Changed 14 months ago by bhutz

  • Authors changed from Michelle Manes to Michelle Manes, Ben Hutz
  • Commit changed from 36ff748509afe07b949c0ba69cf378204867b49c to 2e7dd9a4df1003fcaa8acdebb2e728871142a96a
  • Reviewers set to Patrick Ingram
  • Status changed from needs_work to needs_review

added missing case and a slight optimization of code


New commits:

2e7dd9a21097: added case and slight code optimization

comment:6 Changed 14 months ago by mmanes

  • Reviewers changed from Patrick Ingram to Patrick Ingram, Michelle Manes
  • Status changed from needs_review to needs_work

In the cases of dynatomic_polynomial([0,0]) and dynatomic_polynomial(0), it returns the number 0. Should always return a polynomial, so should be the zero polynomial.

In documentation: We have

R.<x,y> = PolynomialRing(QQ)
S = R.quo(R.ideal(y^2-x+1))
P.<u,v> = ProjectiveSpace(FractionField(S),1)
H = End(P)
f = H([u^2 + S(x^2)*v^2, v^2])
f.dynatomic_polynomial([1,1])

In this case,

f.dynatomic_polynomial([1,1]).parent()

also returns Symbolic Ring.

Might be good to move all of the "Symbolic Ring" examples to the end. A little confusing as currently formatted.

comment:7 Changed 14 months ago by git

  • Commit changed from 2e7dd9a4df1003fcaa8acdebb2e728871142a96a to 93b2e226ae50ff61f5592b26abdbb19898da3682

Branch pushed to git repo; I updated commit sha1. New commits:

a7b366b21097: fix issues from review
93b2e2221097: reorder examples

comment:8 Changed 14 months ago by bhutz

  • Status changed from needs_work to needs_review

comment:9 Changed 14 months ago by mmanes

  • Status changed from needs_review to positive_review

comment:10 Changed 14 months ago by mmanes

  • Milestone changed from sage-7.3 to sage-7.4

comment:11 Changed 14 months ago by vbraun

  • Branch changed from u/bhutz/incorrect_parent_for_dynatomic_polynomial to 93b2e226ae50ff61f5592b26abdbb19898da3682
  • Resolution set to fixed
  • Status changed from positive_review to closed
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