Opened 6 years ago

Closed 3 years ago

#19955 closed enhancement (invalid)

QQbar cleaning 3

Reported by: vdelecroix Owned by:
Priority: major Milestone: sage-duplicate/invalid/wontfix
Component: number fields Keywords:
Cc: Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: #19954, #18356, #20074 Stopgaps:

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Description (last modified by vdelecroix)

This ticket is abandoned as computing with resultants is too slow.

Original description

This is a follow up of #19954 where we:

  • create a new descriptor ANRootRational as a descriptor for roots of irreducible polynomials with rational coefficients
  • write exactification code to go from ANRoot to ANRootRational (i.e. go from a QQbar polynomial anihilator to the minimal polynomial over QQ)
  • get rid of ANUnaryExpr and ANBinaryExpr and use the code from #18356 for addition/subtraction/multiplication/division of anihilator polynomial or minimal polynomial

We might want to force elements of small degrees to lies into number fields (possibly using a global threshold value).

This is part of the task #18333.

Change History (6)

comment:1 Changed 6 years ago by vdelecroix

  • Dependencies changed from #19954, #18356 to #19954, #18356, #20074
  • Summary changed from QQbar cleaning 2 to QQbar cleaning 3

comment:2 Changed 6 years ago by vdelecroix

  • Description modified (diff)

comment:3 follow-up: Changed 3 years ago by mmezzarobba

Hi Vincent,

I think you told me that you no longer wanted to do that, and I agree. It would be nice to have a way of computing directly on ANRoots using resultants (in addition to the version using union(), I think, rather than as a replacement), but ANUnaryExpr and ANBinaryExpr should either remain or be replaced by a more general polynomial descriptor as suggested in #18106.

→ wontfix?

Version 0, edited 3 years ago by mmezzarobba (next)

comment:4 in reply to: ↑ 3 Changed 3 years ago by vdelecroix

  • Authors Vincent Delecroix deleted
  • Description modified (diff)
  • Milestone changed from sage-7.1 to sage-duplicate/invalid/wontfix
  • Status changed from new to needs_review

Hi Marc,

Replying to mmezzarobba:

Hi Vincent,

I think you told me that you no longer wanted to do that, and I agree. It would be nice to have a way of computing directly on ANRoots using resultants (in addition to the version using union(), I think, rather than as a replacement), but ANUnaryExpr and ANBinaryExpr should either remain or be replaced by a more general polynomial descriptor as suggested in #18106 (or perhaps merge with LazyAlgebraic, #24503?)

#24503 is indeed what I intended to do first. That is moving the numerical part of polynomial root evaluation to the real/complex lazy fields.

And on the other hand, computing with resultants is by far too slow if you work with a fixed number field of degree < 10.

→ wontfix?

Looks reasonable to me.

comment:5 Changed 3 years ago by mmezzarobba

  • Status changed from needs_review to positive_review

comment:6 Changed 3 years ago by embray

  • Resolution set to invalid
  • Status changed from positive_review to closed

Presuming these are all correctly reviewed as either duplicate, invalid, or wontfix.

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