Het distributed-computingproject Gimps, wat staat voor Great Internet Mersenne Prime Search, zoekt naar Mersenne-priemgetallen. Dat zijn priemgetallen die precies één kleiner zijn dan een macht van twee, ofwel 2n - 1. De eerste vier n-getallen om de eerste vier Mersenne-priemgetallen mee te vormen zijn 2, 3, 5 en 7, waar respectievelijk 3, 7, 31 en 127 uitkomt. Het benodigde programma heet Prime95 en wordt onder een eigen licentie uitgebracht. Versie 30.3 build 6 is verschenen voor FreeBSD, Linux (32, 64bit) en Windows (32, 64bit), ook kun je natuurlijk de broncode binnen hengelen. De aankondiging en lijst met verbeteringen zien er als volgt uit:
BIG Changes Are Here! Prime95 version 30.3 released.
For almost 25 years, GIMPS has looked for new Mersenne primes by running a primality test on one computer and later running the exact same primality test on another computer to guard against hardware errors having corrupted the first primality test.
A breakthrough by Krzysztof Pietrzak makes it possible to eliminate the second primality test! The first primality test produces a proof file that can be securely verified with less than 0.5% of the work required to re-run the primality test. This breakthrough will nearly double GIMPS' throughput in the long run.
Version 30.3 is now available with PRP proofs. While not a required upgrade, at some point in the future only users running version 30.3 with PRP proofs will be assigned first-time primality tests. Should you run into any problems, support is available at this thread at Mersenne Forum.
Many thanks to Mihai Preda for discovering the paper on the breakthrough and realizing its importance to the GIMPS project. Also, thanks go to Pavel Atnashev for important ideas on adapting the discovery for use by GIMPS.
New features in Version 30.1/30.2/30.3 of prime95.exe
- PRP proofs. This allows GIMPS to double-check a PRP test at less than 1% of the cost of a full PRP test! PRP proofs require lots of temporary disk space. See readme.txt for details. PRP proofs require uploading a large proof file. See readme.txt for details. PRP proof verifications require downloading a modest verification file. See readme.txt for details.
- Proofs automatically uploaded to server in 30.2.
- First time LL, World-record LL, 100M-digit LL work preference is deprecated.
- New resource limits menu choice and dialog box. Consult readme.txt before making changes to these settings. Some options previously in Test/Worker Windows and Options/CPU are moved to the resources dialog box.
- LL-DC and PRP-DC combined into a single work preference.
- Warning raised if temporary disk space is less than 1.5GB -- you may not get first time prime tests.
- Thanks to Mihai Preda, the P-1 probability calculator has been improved. This change results in a lower optimal B1 value and higher optimal B2 value.