cado-nfs - [cado-nfs] Higher ropteffort can produce worse polynomial

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[cado-nfs] Higher ropteffort can produce worse polynomial

From: Robert Balfour <rhb11931@gmail.com>
To: cado-nfs@inria.fr
Subject: [cado-nfs] Higher ropteffort can produce worse polynomial
Date: Mon, 13 Dec 2021 20:47:45 +0000
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Dear all,

Mersenneforum user Gimarel has reported that using a higher ropteffort value can sometimes produce a lower scoring polynomial.

For example, if polyselect_ropt is run on the attached polynomial, with -area 429496729600000000 -Bf 34359738368 -Bg 17179869184, the Murphy-E score of the resulting polynomial is as follows:

-ropteffort 1: 2.026e-09

-ropteffort 10: 1.972e-09

-ropteffort 100: 1.965e-09

Maybe this is just an unlucky consequence of the way the priority queues are managed, but I'm concerned that perhaps at some stage a queue is either being cut too short or not being sorted properly.

I note that when polyselect_ropt is run with -v, the following is printed:

# Info: s1param->nbest_sl: 368 (= size_total_sublattices*ropteffort)

...and despite what this would suggest, the value 368 does not change when ropteffort is increased!

Best regards,

Robert

Attachment: 2_2246M_gimarel.poly
Description: Binary data

[cado-nfs] Higher ropteffort can produce worse polynomial, Robert Balfour, 12/13/2021
- Re: [cado-nfs] Higher ropteffort can produce worse polynomial, Paul Zimmermann, 12/14/2021
- Re: [cado-nfs] Higher ropteffort can produce worse polynomial, Shi Bai, 12/20/2021

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[cado-nfs] Higher ropteffort can produce worse polynomial