#19664: Fix Laurent series comparison and make it more efficient
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Reporter: jdemeyer | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.10
Component: basic arithmetic | Resolution:
Keywords: | Merged in:
Authors: Jeroen Demeyer | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps: #19664
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Changes (by jdemeyer):
* stopgaps: => #19664
Old description:
> The `_cmp_` function for Laurent series can be improved in efficiency.
>
> In particular, this is bad:
> {{{
> sage: R.<x> = LaurentSeriesRing(ZZ)
> sage: x^(10^10) > 0
> ...
> MemoryError:
> }}}
New description:
This is very bad:
{{{
sage: R.<x> = LaurentSeriesRing(ZZ)
sage: f = x^-2 + O(x^0); f
x^-2 + O(1)
sage: g = x^-1 + O(x^0); g
x^-1 + O(1)
sage: f == g
True
sage: f-g
x^-2 - x^-1 + O(1)
}}}
Also this is bad:
{{{
sage: R.<x> = LaurentSeriesRing(ZZ)
sage: x^(10^10) > 0
...
MemoryError:
}}}
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Ticket URL: <http://trac.sagemath.org/ticket/19664#comment:1>
Sage <http://www.sagemath.org>
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