#18416: UniqueRepresentation issue with PowerSeriesRing
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Reporter: vdelecroix | Owner:
Type: defect | Status: new
Priority: critical | Milestone: sage-6.7
Component: algebra | Keywords:
Merged in: | Authors:
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: |
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The power series ring (`sage.rings.power_series_ring.PowerSeriesRing`)
inherits from `UniqueRepresentation`. In the argument of the constructor
there is the precision (`prec`) but it can be modified! Which leads to
wrong behavior
{{{
sage: R1 = PowerSeriesRing(QQ, 'x', 3)
sage: R2 = PowerSeriesRing(QQ, 'x', 3)
sage: R1 is R2
True
sage: R2 = PowerSeriesRing(QQ, 'x', 4)
sage: R1 is R2
False
sage: R2.set_default_prec(3)
sage: R1 == R2
False
}}}
Moreover, a function can modify a power series in use
{{{
sage: def haha()
....: PowerSeriesRing(QQ, 'x').set_default_prec(1)
sage: R = PowerSeriesRing(QQ, 'x')
sage: R.default_prec()
20
sage: haha()
sage: R.default_prec()
1
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/18416>
Sage <http://www.sagemath.org>
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