#15660: QQbar exactify() speed depends on PARI stack size
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Reporter: jdemeyer | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.1
Component: performance | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Description changed by jdemeyer:
Old description:
> From a doctest in `qqbar.py`:
> {{{
> sage: x = polygen(AA)
> sage: %time QQbar.polynomial_root(x^5 - x - 1, CIF(RIF(0.1, 0.2),
> RIF(1.0, 1.1))).imag().minpoly()
> CPU times: user 27.48 s, sys: 0.03 s, total: 27.52 s
> Wall time: 27.77 s
> x^20 - 5/8*x^16 - 95/256*x^12 - 625/1024*x^10 - 5/512*x^8 - 1875/8192*x^6
> + 25/4096*x^4 - 625/32768*x^2 + 2869/1048576
> }}}
> {{{
> sage: pari.allocatemem(1<<30)
> PARI stack size set to 1073741824 bytes
> sage: x = polygen(AA)
> sage: %time QQbar.polynomial_root(x^5 - x - 1, CIF(RIF(0.1, 0.2),
> RIF(1.0, 1.1))).imag().minpoly()
> CPU times: user 2.68 s, sys: 0.16 s, total: 2.83 s
> Wall time: 2.82 s
> x^20 - 5/8*x^16 - 95/256*x^12 - 625/1024*x^10 - 5/512*x^8 - 1875/8192*x^6
> + 25/4096*x^4 - 625/32768*x^2 + 2869/1048576
> }}}
New description:
From a doctest in `qqbar.py`:
{{{
sage: x = polygen(AA)
sage: %time QQbar.polynomial_root(x^5 - x - 1, CIF(RIF(0.1, 0.2), RIF(1.0,
1.1))).imag().exactify()
CPU times: user 28.33 s, sys: 0.02 s, total: 28.35 s
Wall time: 28.38 s
sage: pari.allocatemem(1<<30)
PARI stack size set to 1073741824 bytes
sage: %time QQbar.polynomial_root(x^5 - x - 1, CIF(RIF(0.1, 0.2), RIF(1.0,
1.1))).imag().exactify()
CPU times: user 2.70 s, sys: 0.15 s, total: 2.85 s
Wall time: 2.84 s
}}}
--
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Ticket URL: <http://trac.sagemath.org/ticket/15660#comment:1>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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