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Bug #1113

gcd crashes (Floating point exception)

Added by John Abbott over 6 years ago. Updated over 4 years ago.

Status:
Closed
Priority:
Normal
Assignee:
John Abbott
Category:
Safety
Target version:
CoCoALib-0.99650 November 2019
Start date:
27 Oct 2017
Due date:
% Done:

100%

Estimated time:
Spent time:
0.50 h

Description

In an old file (from 2006) I found two examples where GCD (in CoCoA4) crashes because it runs out of primes; since we use the same old code in CoCoA-5... guess what happens :-(

>>> N := factorial(5500);
>>> F := N*x+N+1;
>>> J := gcd(F^2, F^2+F);

Process cocoa5 floating point exception (core dumped)

Related issues

Related to CoCoALib - Slug #1359: gcd: low degree but big coeffs can be slowNew2019-10-30

History

#1 Updated by John Abbott over 6 years ago

Here is another example (possibly simpler than the previous one?):

gcd(x+1, x+1+factorial(47000));

#2 Updated by John Abbott over 4 years ago

  • Status changed from New to Closed
  • Assignee set to John Abbott
  • Target version changed from CoCoALib-1.0 to CoCoALib-0.99650 November 2019
  • % Done changed from 0 to 100

2019-10-30 I have just tried the example in comment 1, and it no longer crashes. No idea when it was resolved.

I have tried some similar but larger examples; they do not crash either, but they can be very slow.

I'll close this issue, and make a new one about the slug.

#3 Updated by John Abbott over 4 years ago

  • Related to Slug #1359: gcd: low degree but big coeffs can be slow added

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