Go Back > Great Internet Mersenne Prime Search > Software

Thread Tools
Old 2018-12-19, 17:48   #12
kriesel's Avatar
Mar 2017
US midwest

140316 Posts

Originally Posted by nomead View Post
Ok, I know how to change the preferred type of assignment. However, I'm totally unfamiliar with PRP - I guess there's a lot to learn after years away from using Prime95. Is it about as fast as LL?

And in any case, the Jacobi check takes about 15 seconds on the 50M-something exponent I'm double checking at the moment, I would hardly consider that time consuming. Something like 0.13% extra when doing it every three hours.

I somehow missed that option. Thanks for the pointer. It would definitely be better to actually RTFM than just skim through it.
PRP is essentially the same speed on a cpu as LL.
Jacobi check is time consuming enough to be cost prohibitive if performed on a per-iteration basis or after a very small number of LL iterations. A system with an error rate high enough to need that probably ought be repaired or turned off. Jacobi is useful for LL testing on a system with a reasonable reliability level, when only Jacobi testing a small number of times per day is enough. It's possible to have an error rate for which multiple errors flip the Jacobi symbol to the invalid value and back again before the next Jacobi check.

I had a system running that I obtained for under $20. It deteriorated to the point that PRP with Gerbicz check could not make progress on it. Before that it completed a bad LL DC.
Re the permanent save files, you're welcome. Technically, you missed that in the _UN_manual undoc.txt. The program documentation files are all worth reviewing from time to time;
  • our needs/interests may change over time
  • we learn more about the program over time
  • we forget things over time
  • the program's features evolve over time
kriesel is offline   Reply With Quote
Old 2018-12-20, 16:31   #13
Sep 2018

3×23 Posts

Originally Posted by nomead View Post
Yup... M50925509 finished, and as I expected, the residue didn't match the earlier test. Jacobi error check failed about 1/4 into the exponent, and at that point, the testing restarted from the previous saved file. Something must have happened later on in the test, or that previous file was bad as well, and I got that other side of the 50% chance of catching errors.
Ah I was going to nab it but it wasn't showing me it was assigned!

Last fiddled with by irowiki on 2018-12-20 at 16:33
irowiki is offline   Reply With Quote

Thread Tools

Similar Threads
Thread Thread Starter Forum Replies Last Post
Application of Jacobi check to P-1 factoring (paging owftheevil and other coding wizards) kriesel Software 7 2018-09-11 13:32
error during Jacobi check on 330,000,000+ exponent evanh Hardware 5 2018-02-20 03:46
Endlessly Running Jacobi error check on v29.3 emiller Software 10 2017-11-14 10:26
LL testing: Jacobi symbol of the (interim or final) residue minus 2 as error check GP2 Number Theory Discussion Group 33 2017-08-21 22:14
Weird GPU72 Behaviour Gordon GPU to 72 5 2015-01-01 23:41

All times are UTC. The time now is 22:58.

Thu May 13 22:58:28 UTC 2021 up 35 days, 17:39, 0 users, load averages: 2.54, 2.89, 3.01

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.