#17955: LaurentSeriesRing and series_precision
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Reporter: behackl | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.6
Component: symbolics | Keywords: series_precision, asymptotics
Merged in: | Authors:
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: |
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Currently, `LaurentSeriesRing` caches without replacing the default
`default_prec=None` to the global series precision obtainable by
`sage.default.series_precision()` . This leads to the following behavior:
{{{
sage: set_series_precision(5)
sage: R.<x> = LaurentSeriesRing(ZZ)
sage: 1/(1-x)
1 + x + x^2 + x^3 + x^4 + O(x^5)
sage: set_series_precision(3)
sage: R.<x> = LaurentSeriesRing(ZZ)
sage: 1/(1-x)
1 + x + x^2 + x^3 + x^4 + O(x^5)
}}}
Instead, the (second) output should be
{{{
sage: 1/(1-x)
1 + x + x^2 + O(x^3)
}}}
This is fixed by setting `default_prec` to the corresponding global series
precision *before* caching the parent.
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Ticket URL: <http://trac.sagemath.org/ticket/17955>
Sage <http://www.sagemath.org>
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