#13980: numerical noise in variety(RDF)
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Reporter: zimmerma | Owner: AlexGhitza
Type: defect | Status: new
Priority: minor | Milestone: sage-5.7
Component: basic arithmetic | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Comment (by zimmerma):
some progress comparing my machine (tarte.loria.fr) with Sage 5.5 and
"arando" (thanks Dima)
with Sage 5.7.beta0.
On my machine:
{{{
----------------------------------------------------------------------
| Sage Version 5.5, Release Date: 2012-12-22 |
| Type "notebook()" for the browser-based notebook interface. |
| Type "help()" for help. |
----------------------------------------------------------------------
Loading Sage library. Current Mercurial branch is: 12615b
sage: R.<y> = ZZ[]
sage: f
y^7 + 1400000000000000*y^4 + 12600000000000000*y^3 -
9999999999966400000000000000*y^2 - 19999999999964800000000000000*y -
9999999999987200000000000000
sage: r = f.roots(ring=RDF)
sage: r
[(396340.890167, 1)]
sage: RR(r[0][0]).exact_rational()
3404542322665677/8589934592
}}}
On arando:
{{{
----------------------------------------------------------------------
| Sage Version 5.7.beta0, Release Date: 2013-01-21 |
| Type "notebook()" for the browser-based notebook interface. |
| Type "help()" for help. |
----------------------------------------------------------------------
**********************************************************************
* *
* Warning: this is a prerelease version, and it may be unstable. *
* *
**********************************************************************
sage: R.<y> = ZZ[]
sage: r = f.roots(ring=RDF)
sage: r
[(396340.890167, 1)]
sage: RR(r[0][0]).exact_rational()
1702271161332839/4294967296
}}}
Paul
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13980#comment:1>
Sage <http://www.sagemath.org>
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