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Bug #1083

MinPolyQuot: check input (was: MinPolyQuot gives "bad characteristic" error)

Added by John Abbott about 7 years ago. Updated over 6 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Anna Maria Bigatti
Category:
Safety
Target version:
CoCoALib-0.99560
Start date:
28 Jun 2017
Due date:
% Done:

100%

Estimated time:
Spent time:
0.70 h

Description

The followinginput produces an (unexpected) "bad characteristic" error:

use QQ[x[1..3]];
J2 := ideal(x[1]^2 +x[2]^2 -1,  x[1]*x[2]*x[3]^2 +(-1/2)*x[3]^2 -1,  2*x[1] +2*x[2] +4*x[3]);
ReducedGBasis(J2);
---> [x[1] +x[2] +2*x[3],  x[2]^2 +2*x[2]*x[3] +2*x[3]^2 -1/2,  x[3]^4 +(-1/2)*x[3]^2 -1/2]

G2 := gens(J2);
MinPolyQuot(LT(G2[1]),J2,LT(G2[1]));

Update: LT(G2[1]) is not an indeterminate

History

#1 Updated by Anna Maria Bigatti about 7 years ago

It is a problem in the input: the third argument must be an indet
(the indet for the univariate polynomial), instead it is x[1]^2.

I thought I had all the input checking, but I was wrong.
I'll fix it.

#2 Updated by Anna Maria Bigatti about 7 years ago

  • Subject changed from MinPolyQuot: gives "bad characteristic" error to MinPolyQuot: check input (was: MinPolyQuot gives "bad characteristic" error)
  • Category set to Safety
  • Assignee set to Anna Maria Bigatti
  • Target version set to CoCoALib-0.99560
  • % Done changed from 0 to 30

Done and checked-in.
A cleaner way to call it is

t := indet(RingQQt(1), 1);
use QQ[x[1..3]];
J2 := ideal(x[1]^2 +x[2]^2 -1,  x[1]*x[2]*x[3]^2 +(-1/2)*x[3]^2 -1,  2*x[1] +2*x[2] +4*x[3]);
G2 := gens(J2);
MinPolyQuot(LT(G2[1]), J2, t);

#3 Updated by Anna Maria Bigatti about 7 years ago

  • Description updated (diff)

#4 Updated by Anna Maria Bigatti about 7 years ago

Reminder for myself: update the manual, clarify the meaning, and show evaluation homomorphism.

#5 Updated by John Abbott over 6 years ago

  • Status changed from New to Closed
  • % Done changed from 30 to 100

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