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Feature #780

GroebnerFan/ExternalLib-GFan: improve package

Added by Anna Maria Bigatti over 8 years ago. Updated almost 7 years ago.

Status:
In Progress
Priority:
Normal
Category:
Improving
Target version:
Start date:
24 Sep 2015
Due date:
% Done:

20%

Estimated time:
20.00 h
Spent time:

Description

First prototype is working.
Investigate and improve it, and implement it in cocoalib.


Related issues

Related to CoCoALib - Feature #762: ExternalLib-GFan: first prototypeClosed2015-08-28

Related to CoCoA-5 - Feature #903: New function CallOnGroebnerFanIdeals: call function on GFan idealsClosed2016-07-04

Related to CoCoALib - Slug #1049: GroebnerFan: slow examplesIn Progress2017-04-19

History

#1 Updated by Anna Maria Bigatti over 8 years ago

  • Status changed from New to In Progress
  • % Done changed from 0 to 20

In the package there are lots of operations on integers and those would surely be faster in cocoalib (at some point).

But I did make some improvements:
- the function "matrix" in cocoa-5, using the function SetRow (and that's good in general ;-)
- a minor improvement in MarkedPolynomialsToInequalities (just to touch fewer INTs)
- in GroebnerBasisFlip: ideal(apply(f, gens(I))) instead of ideal(apply(f, GBasis(I))) (the ideals are equal, and gens are generally simpler and fewer)

With these changes I get the answer in 68s instad of 82s.
(That's a decent start)

  /**/ Use R ::= QQ[a,b,c];
  /**/ I := ideal(a^5+b^3+c^2-1, b^2+a^2+c-1, c^3+a^6+b^5-1);
  /**/ l:=AllReducedGroebnerBases(I);  len(l);

What I find strange is that I get these two cumulative times:
GFanGetFacets: 21.999sec
GFanRelativeInteriorPoint: 4.599sec
and these alone take much longer than the complete computation in gfan.
Can the overhead be so bad?

#2 Updated by Anna Maria Bigatti about 8 years ago

  • Target version changed from CoCoALib-0.99540 Feb 2016 to CoCoALib-0.99542 spring 2016

#3 Updated by Anna Maria Bigatti about 8 years ago

  • Target version changed from CoCoALib-0.99542 spring 2016 to CoCoALib-1.0

#4 Updated by Anna Maria Bigatti over 7 years ago

  • Related to Feature #903: New function CallOnGroebnerFanIdeals: call function on GFan ideals added

#5 Updated by Anna Maria Bigatti almost 7 years ago

  • Related to Slug #1049: GroebnerFan: slow examples added

#6 Updated by Anna Maria Bigatti almost 7 years ago

Abbott found this gives error (#1049)

GroebnerFanIdeals(ideal(x*y,y^3+x,y^3));

I investigated: it's an error in ReducedGBasis (argh)

#7 Updated by Anna Maria Bigatti almost 7 years ago

  • Subject changed from ExternalLib-GFan: improve package to GroebnerFan/ExternalLib-GFan: improve package

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