mersenneforum.org over trial factoring
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 2004-08-11, 10:54 #1 JFB   Jun 2004 France [UTC+2] 2×7 Posts over trial factoring hello. out of result.txt: 33,872,239 trial factoring up to 72 33,697,229 up to 70 34,004,779 up to 70 (these are only examples). I've got 2 questions : - is it done by manual overriding worktodo.ini ? - is it worth factoring further 69 ? thanks JFB.
2004-08-11, 14:48   #2
PrimeCruncher

Sep 2003

2BE16 Posts

Quote:
 Originally Posted by JFB hello. out of result.txt: 33,872,239 trial factoring up to 72 33,697,229 up to 70 34,004,779 up to 70 (these are only examples). I've got 2 questions : - is it done by manual overriding worktodo.ini ? - is it worth factoring further 69 ? thanks JFB.
It is done by using FactorOverride in either prime or local.ini (don't remember which). From the Prime95 help file on determining factoring levels:

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. If a factor is found we can avoid running both the first-time and double-check primality tests.

 2004-08-11, 17:49 #3 JFB   Jun 2004 France [UTC+2] 2×7 Posts Thanks PrimeCruncher, I found FactorOverride parameter in Undocumented Features help. But its purpose is to limit how far the program tries to factor a number, not to go beyond Prime95 default settings. Are you sure this is the way to deeper the factoring depth ? Have you tested it ? JFB.
2004-08-11, 17:55   #4
PrimeCruncher

Sep 2003

10101111102 Posts

Quote:
 Originally Posted by JFB Thanks PrimeCruncher, I found FactorOverride parameter in Undocumented Features help. But its purpose is to limit how far the program tries to factor a number, not to go beyond Prime95 default settings. Are you sure this is the way to deeper the factoring depth ? Have you tested it ? JFB.
I haven't tested it, no, but I believe that is the way to deeper factoring depths. I haven't seen anything else that would do that.

2004-08-11, 18:17   #5
ET_
Banned

"Luigi"
Aug 2002
Team Italia

2·29·83 Posts

Quote:
 Originally Posted by PrimeCruncher I haven't tested it, no, but I believe that is the way to deeper factoring depths. I haven't seen anything else that would do that.
I tried it, and it worked fine

You can trial-factoring deeper with that option set.

Luigi

 2004-08-11, 18:53 #6 JFB   Jun 2004 France [UTC+2] 2·7 Posts Thanks Luigi. "This feature should not be used with the Primenet server" (Undoc.Feat.). Did you encounter problem using it ? JFB.
2004-08-11, 18:56   #7
PrimeCruncher

Sep 2003

2·33·13 Posts

Quote:
 Originally Posted by JFB Thanks Luigi. "This feature should not be used with the Primenet server" (Undoc.Feat.). Did you encounter problem using it ? JFB.
It shouldn't be used with the PrimeNet server. It works fine for LMH (I have FactorOverride=62 set on my P3-850; it's working on the 58-58.5M range).

 2004-08-11, 19:33 #8 JFB   Jun 2004 France [UTC+2] 11102 Posts I don't understand, PrimeCruncher. Didn't you say you haven't tested it ? Mmm... Maybe I'm too newB for that matter... I will think about it some time. Anyway thanks to both of you ! JFB.
 2004-08-11, 19:34 #9 Prime95 P90 years forever!     Aug 2002 Yeehaw, FL 749210 Posts I don't think using that feature to factor deeper than normal will cause the PrimeNet server any grief.
 2004-08-11, 20:05 #10 JFB   Jun 2004 France [UTC+2] E16 Posts I take it from whom it comes from ! Il ne faut pas ĂȘtre plus royaliste que le Roi. Thank you Georges. JFB.
 2004-08-11, 21:06 #11 Axel Fox     May 2003 25·3 Posts If I'm not mistaking (and correct me if I'm wrong, George), the FactorOverride parameter is ignored when you use PrimeNet. If "Use Primenet" is unchecked, the program will factor from the number in the worktodo.ini file to the FactorOverride parameter (or to the standard value if FactorOverride is not set). So, if "Use Primenet" is checked, it always factors to the standard value.

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