#10063: Some determinants can not be computed
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Reporter: tmonteil | Owner: tmonteil
Type: defect | Status: needs_review
Priority: critical | Milestone:
Component: commutative algebra | Keywords: determinant, ring,
ideal
Author: Thierry Monteil | Upstream: N/A
Reviewer: Mike Hansen, Sébastien Labbé | Merged:
Work_issues: |
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Comment(by slabbe):
> Should we think to clean the whole `determinant` code?
Maybe. I don't know. But, I don't feel I am the determinant expert that
could rethink/refactor/improve that code.
Although, I reviewed your most recent patch (`
trac_10063-determinant_not_computed_in_some_rings_bugfix_attempt_4-tm.patch`).
I was able to reproduce the problem on my computer. The problem is indeed
fixed by the patch. All test passed in the repository `sage/matrix`.
Documentation builds fine.
The problem originated from a `NotImplementedError` when computing
`R.is_field()` in the case where `algorithm=None` (see below). So your new
code instead tries to compute `R.is_field()` and if `R.is_field()` raises
a `NotImplementedError` you consider this as `R.is_field() == False`. This
computation is done only if algorithm is None so that the method doesn't
get slower. You also followed my earlier advise, that is, the try
statement only tries what is necessary.
Hence, from the knowledge I have, I am OK with giving a positive review to
this ticket. Maybe Mike Hanson or Jason have comments, so I wait 24 hours,
and then I will change the status to positive review.
Sébastien
PS : The `is_field` method is not implemented for the following ring
(should we open a ticket for it?):
{{{
sage: A = GF(2)['x,y,z']
sage: A.inject_variables()
Defining x, y, z
sage: R = A.quotient(x^2 + 1).quotient(y^2 + 1).quotient(z^2 + 1)
sage: R.is_field()
Traceback (most recent call last):
NotImplementedError:
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10063#comment:14>
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