#12026: root finding misses a root over QQbar
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Reporter: was | Owner: AlexGhitza
Type: defect | Status: new
Priority: critical | Milestone: sage-4.8
Component: algebra | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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{{{
sage: A = matrix(QQ, 8, lambda i, j: 1/(i + j + 1))
sage: f = A.charpoly()
sage: f.degree()
8
sage: f.is_squarefree() # so f must have 8 roots over the algebraic
closure.
True
sage: len(f.roots(QQbar)) # VERY BAD
7
}}}
At least the roots that are found are really roots:
{{{
sage: [f(a[0])==0 for a in f.roots(QQbar)]
[True, True, True, True, True, True, True]
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12026>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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