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Slug #1392

ApproxSolve: another slow example

Added by John Abbott over 4 years ago. Updated over 2 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Anna Maria Bigatti
Category:
enhancing/improving
Target version:
CoCoA-5.4.0
Start date:
13 Jan 2020
Due date:
% Done:

100%

Estimated time:
1.55 h
Spent time:
1.55 h

Description

Here is another seemingly simple system where ApproxSolve is unexpectedly slow

 use QQ[x,y,z];
 L := [x^4 -y*z^3 +z^4,  y^4 -x^2*y*z +2*x*z^3,  z^4 -x*y^2 +3*y^3];
 solns := ApproxSolve(L);

Related issues

Related to CoCoA-5 - Slug #907: ApproxSolve very slow on this exampleClosed2016-07-14

History

#1 Updated by John Abbott over 4 years ago

It took about 3mins on my computer: anyway not more than 220s.

#2 Updated by Anna Maria Bigatti over 4 years ago

  • Related to Slug #907: ApproxSolve very slow on this example added

#3 Updated by Anna Maria Bigatti over 4 years ago

  • Status changed from New to In Progress
  • Assignee set to Anna Maria Bigatti
  • % Done changed from 0 to 50

We (Robbiano and I) found a way to solve it quickly: compute the radical first!

/**/ t_0:=CpuTime(); SA := ApproxSolve(gens(radical(ideal(L)))); TimeFrom(t_0);
0.949

Obviously, when I wrote the code in ApproxSolve, the radical was not as good as it is now ;-)
I'll change the code in ApproxSolve.cpkg5 so that it computes the radical internally.

#4 Updated by John Abbott about 3 years ago

  • Description updated (diff)
  • Status changed from In Progress to Resolved
  • % Done changed from 50 to 80

The example given is quite quick now (0.5s on my computer).
Marking as "resolved" (don't know by whom or when).

#5 Updated by John Abbott over 2 years ago

  • Description updated (diff)
  • Status changed from Resolved to Closed
  • % Done changed from 80 to 100
  • Estimated time set to 1.55 h

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