#18416: UniqueRepresentation issue with PowerSeriesRing
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Reporter: vdelecroix | Owner:
Type: defect | Status: new
Priority: critical | Milestone: sage-6.7
Component: algebra | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Description changed by vdelecroix:
Old description:
> 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
> }}}
New description:
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: R = PowerSeriesRing(QQ, 'x', 3)
sage: R.default_prec()
3
sage: R.set_default_prec(19)
sage: PowerSeriesRing(QQ, 'x', 3).default_prec()
19
}}}
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
}}}
--
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Ticket URL: <http://trac.sagemath.org/ticket/18416#comment:1>
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