#19946: Asymptotic Ring: cannot construct 2^n when coefficient ring is SR
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Reporter: cheuberg | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-7.1
Component: asymptotic expansions | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Description changed by cheuberg:
Old description:
> The following is unexpected:
> {{{
> sage: A.<n> = AsymptoticRing('QQ^n * n^QQ', SR)
> sage: 2^n
> Traceback (most recent call last):
> ...
> ArithmeticError: Cannot construct 2^n in Growth Group QQ^n * n^QQ
> > *previous* TypeError: unsupported operand parent(s) for '*':
> 'Growth Group QQ^n * n^QQ' and 'Growth Group SR^n'
> }}}
> The only work-around I found until now is
> {{{
> sage: A(AsymptoticRing(growth_group='QQ^n', coefficient_ring=ZZ)('2^n'))
> 2^n
> }}}
New description:
The following is unexpected:
{{{
sage: A.<n> = AsymptoticRing('QQ^n * n^QQ', SR)
sage: 2^n
Traceback (most recent call last):
...
ArithmeticError: Cannot construct 2^n in Growth Group QQ^n * n^QQ
> *previous* TypeError: unsupported operand parent(s) for '*':
'Growth Group QQ^n * n^QQ' and 'Growth Group SR^n'
}}}
The only work-around I found until now is
{{{
sage: A(AsymptoticRing(growth_group='QQ^n', coefficient_ring=ZZ)('2^n'))
2^n
}}}
Once this is fixed, the work-around should be removed from #19532
(`asymptotic_expansions.SingularityAnalysis`).
--
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Ticket URL: <http://trac.sagemath.org/ticket/19946#comment:1>
Sage <http://www.sagemath.org>
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