#15654: PARI discriminant speed depends on stack size
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Reporter: jdemeyer | Owner:
Type: defect | Status: new
Priority: critical | 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:
> This is weird and bad:
> {{{
> sage: x = polygen(ZpFM(3,10))
> sage: p = ((x-1)^50 + x)._pari_init_()
> sage: %time pari(p).poldisc()
> CPU times: user 59.20 s, sys: 0.01 s, total: 59.21 s
> Wall time: 59.35 s
> 2*3 + 3^4 + 2*3^6 + 3^7 + 2*3^8 + 2*3^9 + O(3^10)
> sage: %time gp(p).poldisc()
> CPU times: user 0.00 s, sys: 0.01 s, total: 0.01 s
> Wall time: 0.16 s
> 2*3 + 3^4 + 2*3^6 + 3^7 + 2*3^8 + 2*3^9 + O(3^10)
> }}}
>
> The problem isn't PARI itself (given the speed of `gp`), it's somehow the
> PARI interface in Sage.
>
> This happens both before and after the various PARI cleanup tickets in
> Sage 6.1.
New description:
This is weird and bad:
{{{
sage: x = polygen(ZpFM(3,10))
sage: p = ((x-1)^50 + x)._pari_init_()
sage: %time pari(p).poldisc()
CPU times: user 52.73 s, sys: 0.00 s, total: 52.73 s
Wall time: 52.82 s
2*3 + 3^4 + 2*3^6 + 3^7 + 2*3^8 + 2*3^9 + O(3^10)
sage: pari.allocatemem(2<<20)
PARI stack size set to 2097152 bytes
sage: %time pari(p).poldisc()
CPU times: user 0.08 s, sys: 0.00 s, total: 0.08 s
Wall time: 0.08 s
2*3 + 3^4 + 2*3^6 + 3^7 + 2*3^8 + 2*3^9 + O(3^10)
}}}
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Ticket URL: <http://trac.sagemath.org/ticket/15654#comment:2>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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