20210416, 14:02  #1 
"David Kirkby"
Jan 2021
Althorne, Essex, UK
3×5×13 Posts 
Is the website outdated, or me stupid?
First, I'm not a mathematician, so its probably the latter. According to this page on the maths
https://www.mersenne.org/various/math.php when discussing trial factoring, it says "Now the only question remaining is how much trial factoring should be done? The answer depends on three variables: the cost of factoring, the chance of finding a factor, and the cost of a primality test. The formula used is: factoring_cost < chance_of_finding_factor * 2 * primality_test_cost That is, the time spent factoring must be less than the expected time saved." Where does the factor of 2 come from? Is it outdated now PRP tests are used, so that a LL test does not have to be performed twice? Or is it still current? I can't seem to get my head around that one  part of me thinks it is right, but part of me thinks it is wrong. Being the website admin, director, loo cleaner etc for my own company, https://www.kirkbymicrowave.co.uk/ I know what a nightmare it is trying to keep a website up to date, but I'm not even convinced it is outdated, but suspect it might be. Dave Last fiddled with by drkirkby on 20210416 at 14:03 
20210416, 14:11  #2 
6809 > 6502
"""""""""""""""""""
Aug 2003
101×103 Posts
2×4,783 Posts 
It is outdated. The 2 is from 2 LL tests. Mersenne.ca and GPU72 have started to factor in the savings, wrt bit level. Since TFing each bit level is double the effort of the bit level below, that translates to do 1 less bit level.

20210416, 14:12  #3  
Jun 2003
2·3·827 Posts 
Quote:


20210416, 20:11  #4  
"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest
5,119 Posts 
Quote:
For PRP with GEC and proof, the numbers are much better; ~1.01, including GEC which is ~0.2% for block size 1000, thanks to the great reduction in verification by the VDF based proof generation and CERT, and the quick error detection and recovery along the way of GEC. The value depends on the proof power and whether the initial verification succeeds. For the usual case, proof power 8 or 9, and successful verification the first time, total test and verification effort is <1.01 times a single PRP test without proof. See also https://www.mersenneforum.org/showpo...45&postcount=4 

20210417, 00:07  #5 
"David Kirkby"
Jan 2021
Althorne, Essex, UK
3×5×13 Posts 
Who could update the website?

20210417, 23:56  #6 
Mar 2019
USA
2^{2}×13 Posts 
If whomever does update the site, can you please add one more column to the following page:
https://www.mersenne.org/worktypes/ That references the numerical value of the work preference in prime95? 
20210418, 02:05  #7 
6809 > 6502
"""""""""""""""""""
Aug 2003
101×103 Posts
2×4,783 Posts 

20210418, 08:58  #8  
"David Kirkby"
Jan 2021
Althorne, Essex, UK
3·5·13 Posts 
Quote:
Code:
Use the following values to select a work type: 0  Whatever makes the most sense 150  First time prime tests 152  World record sized numbers to prime test 151  Doublecheck prime tests 2  Trial factoring 4  P1 factoring 153  100 million digit numbers to prime test 160  First time PRP on Mersenne cofactors 161  Doublecheck PRP on Mersenne cofactors 5  ECM for first factors of Mersenne numbers 8  ECM on Mersenne cofactors 6  ECM on Fermat numbers 1  Trial factoring to low limits 

20210418, 10:10  #9 
Sep 2006
Brussels, Belgium
3206_{8} Posts 
The numerical values are used in the prime.txt configuration file for both mprime and Prime95 ... and to communicate with PrimeNet. But only the mprime user interface confronts one with them directly.
It would indeed be a good idea to add that column to the table on the PrimeNet Assignment Work Types page, the v5.0 PrimeNet Web API 0.97 page can also benefit by being updated ;) Jacob 
20210418, 14:17  #10 
6809 > 6502
"""""""""""""""""""
Aug 2003
101×103 Posts
10010101011110_{2} Posts 
I "fixed" the mprime vs Prime95 reference. With mprime you need to use the numbers, Prime95 not so much. I did not fix the website. Only George, Aaron, and James (a little) have access to make changes to Mersenne.org.

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