#17452: LinearCode should check the rank
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Reporter: vdelecroix | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.5
Component: coding theory | Keywords:
Merged in: | Authors: Vincent Delecroix
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: |
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Hi,
In [http://ask.sagemath.org/question/24504/a-bug-in-computing-minimum-
distance-coding-theory/ a question on ask.sagemath.org] was presented the
following problem
{{{
sage: K = GF(4,"a")
sage: a = K.gen()
sage: G = Matrix([[a, a + 1, 1, a + 1, 1, 0, 0],
....: [0, a, a + 1, 1, a + 1, 1, 0],
....: [0, 0, a, a + 1, 1, a + 1, 1],
....: [a + 1, 0, 1, 0, a + 1, 1, a + 1],
....: [a, a + 1, a + 1, 0, 0, a + 1, 1],
....: [a + 1, a, a, 1, 0, 0, a + 1],
....: [a, a + 1, 1, a + 1, 1, 0, 0]])
sage: C = LinearCode(G)
sage: C.minimum_distance()
5
}}}
whereas the code has distance 3. The problem is that the input matrix does
not has full rank... but this is never tested!
--
Ticket URL: <http://trac.sagemath.org/ticket/17452>
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