20140605, 10:48  #1 
Dec 2002
360_{16} Posts 
option for finding multiple factors during trial factoring
I tried undoc, readme and google but couldn't find the information I was looking for. If I got it right mprime (or prime95) stops looking for more factors when it has found a factor during trial factoring, so the line
Factor=N/A,some_exponent,0,56 returns 1 factor at most. Again, if I am correct. Is there an option to force it to find all factors between 0 and 56 bits using only trial factoring? 
20140605, 11:59  #2 
Romulan Interpreter
"name field"
Jun 2011
Thailand
10100000100010_{2} Posts 
No. For GIMPS (i.e. finding primes) the exponent falls from grace once a factor is found (i.e. is composite).
And you should not use P95 anymore for doing TF. This because GPUs do TF from 100 to 300 times faster. Even if you have an antediluvian CPU/system which could not run P1 or DC (i.e. slow, no memory), keeping it running for just TF is not justified economically [edit: better load yafu and work some aliquots on it]. You could get a lowrange GPU and do the same TF work in less time and with lower electricity bill. My two cents. Everybody is free to do whatever work he wants with his resources. Last fiddled with by LaurV on 20140605 at 12:00 
20140605, 13:27  #3 
"Daniel Jackson"
May 2011
14285714285714285714
3×251 Posts 
If you want to do more than 1 factor, use factor5. That doesn't stop at the 1st factor. (Google it if you need to)
Last fiddled with by Stargate38 on 20140605 at 13:28 Reason: fix smilie 
20140605, 14:32  #4 
Dec 2002
2^{5}×3^{3} Posts 

20140605, 15:18  #5 
"Mr. Meeseeks"
Jan 2012
California, USA
2^{7}×17 Posts 
Yes... it's really not worth TF'ing on the CPU at all in my opinion... especially with factor5. I think it was mainly made/optimized for the very high ranges (Operation Billion Digits)
For example: TF'ing a 55M number from 58 to 59 bits takes 51 seconds on a haswell core. 
20140605, 15:23  #6  
"Bob Silverman"
Nov 2003
North of Boston
2^{2}·1,877 Posts 
Quote:
GIMPS is looking for Mersenne Primes. The purpose of TF is to quickly eliminate candidates that have small prime factors so that they need not run a full LL test. Once a factor is found, we know the number is composite. Move on. 

20140605, 15:30  #7 
Sep 2002
Database er0rr
7·641 Posts 
One possible use might be prp testing the remaining cofactor

20140605, 15:34  #8 
"Bob Silverman"
Nov 2003
North of Boston
1D54_{16} Posts 

20140605, 15:49  #9 
Sep 2002
Database er0rr
7·641 Posts 
Maybe to top this The Prime Pages table for Mersenne cofactors
However, if it is beyond proof, then it might be added to Henri Lifchitz's PRP database. Last fiddled with by paulunderwood on 20140605 at 16:01 
20140605, 15:52  #10 
"Forget I exist"
Jul 2009
Dartmouth NS
2·3·23·61 Posts 
I could see eliminating possible candidates for other prime exponents if the factor is still small enough to be useful, for example 7,21,35,49,... all divide by 7
and are 1 mod : Code:
(12:44) gp > forstep(x=1,100,2,a=7*x;print(factor(a1))) [2, 1; 3, 1] [2, 2; 5, 1] [2, 1; 17, 1] [2, 4; 3, 1] [2, 1; 31, 1] [2, 2; 19, 1] [2, 1; 3, 2; 5, 1] [2, 3; 13, 1] [2, 1; 59, 1] [2, 2; 3, 1; 11, 1] [2, 1; 73, 1] [2, 5; 5, 1] [2, 1; 3, 1; 29, 1] [2, 2; 47, 1] [2, 1; 101, 1] [2, 3; 3, 3] [2, 1; 5, 1; 23, 1] [2, 2; 61, 1] [2, 1; 3, 1; 43, 1] [2, 4; 17, 1] [2, 1; 11, 1; 13, 1] [2, 2; 3, 1; 5, 2] [2, 1; 157, 1] [2, 3; 41, 1] [2, 1; 3, 2; 19, 1] [2, 2; 89, 1] [2, 1; 5, 1; 37, 1] [2, 7; 3, 1] [2, 1; 199, 1] [2, 2; 103, 1] [2, 1; 3, 1; 71, 1] [2, 3; 5, 1; 11, 1] [2, 1; 227, 1] [2, 2; 3, 2; 13, 1] [2, 1; 241, 1] [2, 4; 31, 1] [2, 1; 3, 1; 5, 1; 17, 1] [2, 2; 131, 1] [2, 1; 269, 1] [2, 3; 3, 1; 23, 1] [2, 1; 283, 1] [2, 2; 5, 1; 29, 1] [2, 1; 3, 3; 11, 1] [2, 5; 19, 1] [2, 1; 311, 1] [2, 2; 3, 1; 53, 1] [2, 1; 5, 2; 13, 1] [2, 3; 83, 1] [2, 1; 3, 1; 113, 1] [2, 2; 173, 1] 
20140605, 16:43  #11  
"Bob Silverman"
Nov 2003
North of Boston
7508_{10} Posts 
Quote:


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