Opened 16 months ago

Last modified 12 months ago

#27255 new defect

conversion in multivariate polynomial ring fails

Reported by: dkrenn Owned by:
Priority: major Milestone:
Component: algebra Keywords:
Cc: Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: #22333 Stopgaps:


Trying to "group" the coefficients like

sage: P.<a, b, n> = QQ[]
sage: N = PolynomialRing(QQ, 'n')
sage: AB = PolynomialRing(N, 'a, b')
sage: AB(a*n + a*n^2)

fails with

TypeError: not a constant polynomial

but the result should be

(n + n^2)*a

As an interesting side note, the Laurent polynomial ring can do it:

sage: L = LaurentPolynomialRing(QQ, 'a, b, n')
sage: LN = LaurentPolynomialRing(QQ, 'n')
sage: LAB = LaurentPolynomialRing(LN, 'a, b')
sage: LAB(L(a*n + a*n^2))
(n + n^2)*a

The Laurent polynomial ring can do this since #21855. And #22333 is about reusing this code, so there is a good chance that #22333 fixes this as well.

Change History (4)

comment:1 Changed 16 months ago by dkrenn

  • Type changed from PLEASE CHANGE to defect

comment:2 Changed 16 months ago by jdemeyer

This might be fixed by #25558 (which is work in progress).

comment:3 Changed 14 months ago by embray

  • Milestone changed from sage-8.7 to sage-8.8

Ticket retargeted after milestone closed (if you don't believe this ticket is appropriate for the Sage 8.8 release please retarget manually)

comment:4 Changed 12 months ago by embray

  • Milestone sage-8.8 deleted

As the Sage-8.8 release milestone is pending, we should delete the sage-8.8 milestone for tickets that are not actively being worked on or that still require significant work to move forward. If you feel that this ticket should be included in the next Sage release at the soonest please set its milestone to the next release milestone (sage-8.9).

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