#10221: problem in rounding (RealField)
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Reporter: zimmerma | Owner: AlexGhitza
Type: defect | Status: new
Priority: minor | Milestone: sage-4.6.1
Component: basic arithmetic | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Consider the following with Sage 4.4.4:
{{{
sage: RD = RealField(53, rnd='RNDD')
sage: RU = RealField(53, rnd='RNDU')
sage: a=RD(1/3)
sage: RU(1/a)
3.00000000000000
sage: RU(1/a.exact_rational())
3.00000000000001
}}}
I would expect both results to be equal, since a is exactly representable
in 53-bit precision. However it seems in {{{RU(1/a)}}}
that {{{1/a}}} is evaluated with rounding down, whereas I would
expect it evaluated with rounding up.
Maybe {{{1/a}}} is first evaluated before {{{RU}}} is called on it?
Paul
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10221>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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