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Bug #1690

resultant gives wrong answer if an arg has deg 0

Added by John Abbott over 1 year ago. Updated over 1 year ago.

Status:
Closed
Priority:
High
Assignee:
John Abbott
Category:
Maths Bugs
Target version:
CoCoALib-0.99850
Start date:
31 Jul 2022
Due date:
% Done:

100%

Estimated time:
0.55 h
Spent time:
0.50 h

Description

The following incorrectly returns 0

f := x^3-2;
resultant(f, 3*x/x, x);

History

#1 Updated by John Abbott over 1 year ago

  • Status changed from New to Feedback
  • Assignee set to John Abbott
  • % Done changed from 0 to 80

The code did not properly handle the "edge case" when one of the input polys was a factor of the other.
If the factor is not constant then the result is zero; but if the factor is constant then the result is non-zero!

Fixed. Added a test in test-exbugs.C
[will check in soon... if I can remember how]

#2 Updated by John Abbott over 1 year ago

  • Status changed from Feedback to Closed
  • % Done changed from 80 to 100
  • Estimated time set to 0.55 h

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