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Feature #223

Automatic mapping of RingElems

Added by John Abbott over 11 years ago. Updated almost 10 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Anna Maria Bigatti
Category:
New Function
Target version:
CoCoALib-0.99534 Seoul14
Start date:
08 Aug 2012
Due date:
% Done:

100%

Estimated time:
Spent time:
1.35 h

Description

Bruns has "complained" about the lack of automatic mapping of RingElem values from a coeff ring to a poly ring.

Automatic mapping of RingElem values is being considered for CoCoA-5, so why forbid it in CoCoALib?

One possible reason is speed of execution. Still it seems unfair/unreasonable to make the programmer's life difficult just because there are some circumstances where "careless programming" might lead to a measurable reduction in performance.

Note that not having automatic mapping in CoCoALib will make it harder to port CoCoA-5 programs into CoCoA-5 -- perhaps even impossible in some cases?

AMB March 2013: added RingElem(R, rhs)

Related issues

Related to CoCoA-5 - Feature #7: Automatic mapping between (some) ringsResolved2011-10-20

Related to CoCoALib - Feature #221: Better RingElemsClosed2012-08-08

Related to CoCoALib - Feature #253: W.Bruns's wish listClosed2012-10-04

Related to CoCoA-5 - Design #637: Undesirable consequence of automatic mapping of RingElems?Closed2014-10-23

Related to CoCoALib - Feature #645: Automatic mapping of RingElem: user selectable at run-time (GlobalManager?)Rejected2014-11-04

History

#1 Updated by Christof Soeger over 11 years ago

To make the conversion at least easier a constructor like in #7 note-4 would be helpful: RingElem(R, x)

If an change of the ring of RingElem by assigning a new value will be allowed as proposed in issues #221 also changing the ring of an existing RingElem by mapping it into a given ring without creating a new element could be usefull.

#2 Updated by Anna Maria Bigatti about 11 years ago

  • Category set to New Function
  • Status changed from New to Resolved
  • Assignee set to Anna Maria Bigatti
  • Target version set to CoCoA-5.0.9
  • % Done changed from 0 to 70

I added RingElem(R, rhs) with rsh a RingElem in a ring S such that there exists a CanonicalHom S->R
(both to CoCoALib and CoCoA-5, but no documentation, manual, test, cvs,.. yet!)

/**/ Use R;
/**/ K := NewFractionField(R);
/**/ 1/RingElem(K, x^2-x);
1/(x^2 -x)

For those able to read between the bits: it's a giant leap for mankind!

#3 Updated by Anna Maria Bigatti about 11 years ago

  • Status changed from Resolved to Feedback
  • % Done changed from 70 to 90

#4 Updated by Anna Maria Bigatti about 11 years ago

cvs-ed

#5 Updated by Anna Maria Bigatti about 10 years ago

  • Target version changed from CoCoA-5.0.9 to CoCoALib-0.99534 Seoul14

#6 Updated by John Abbott almost 10 years ago

  • Status changed from Feedback to Closed
  • % Done changed from 90 to 100

Closing this issue, but leaving #7 open. This is fine as far as it goes.

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