#17891: rational powers of real interval field element (containing 0) give NaN
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Reporter: dkrenn | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.6
Component: misc | Keywords:
Merged in: | Authors:
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: |
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We have
{{{
sage: RIF(-1,1)^QQ(1)
[.. NaN ..]
sage: RIF(-1,1)^RIF(1)
[.. NaN ..]
}}}
whereas
{{{
sage: RIF(-1,1)^ZZ(1)
0.?
}}}
More generally, we it works for integers
{{{
sage: RIF(-1,1)^ZZ(123456)
0.?
}}}
as well as for the rational or RIF-element 2
{{{
sage: RIF(-1,1)^QQ(2)
1.?
sage: RIF(-1,1)^RIF(2)
1.?
}}}
but not for any other rational or RIF-element, e.g.
{{{
sage: RIF(-1,1)^QQ(3)
[.. NaN ..]
sage: RIF(-1,1)^QQ(4)
[.. NaN ..]
}}}
The reason seems to be
{{{
sage: log(RIF(-1,1))
[.. NaN ..]
}}}
The NaN-answer can be considered as wrong, since the true result is a
number and can be calculated; it's a limitation of the algorithm.
--
Ticket URL: <http://trac.sagemath.org/ticket/17891>
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