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Slug #1757

gcd(f,f) is slow

Added by John Abbott 9 months ago. Updated 2 months ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
Improving
Target version:
CoCoALib-0.99880
Start date:
23 Jul 2023
Due date:
% Done:

0%

Estimated time:
Spent time:
0.65 h

Description

Consider making a special case of gcd(f,f) or indeed gcd(f,k*f) where k is a scalar.

History

#1 Updated by John Abbott 9 months ago

Here is just 1 example illustrating the point:

/**/ f := cyclotomic(20,x)*cyclotomic(257*307,x);
/**/ t0:=CpuTime(); h := gcd(f,f); TimeFrom(t0);
3.009

#2 Updated by John Abbott 7 months ago

I have just tried computing RootBound(f). It is taking ages :-( [about 360s]
No doubt the problem is that it takes a long time to compute the graeffe transform.
Moreover it is doing 5 graeffe transforms -- why???

#3 Updated by John Abbott 2 months ago

  • Target version changed from CoCoALib-0.99850 to CoCoALib-0.99880

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