Mersenne: ECM Factoring
Hi, I need some help. I would like to look for a factor of a mersenne prime in a specific area. For example, for a mersenne exponent of say 40,000,000. I want to use the Prime95b program, (v19 I guess), to search for a factor in a specific range from, say, 2^40 to 2^50. I do not understand the ECM factoring instuctions included with Prime95. You can also edit the worktodo.ini file directly. For example: ECM=751,300,0,100,0,0,0,24 The first value is the exponent. The second value is bound #1. The third value is bound #2 - leave it as zero. The fourth value is the number of curves to test. The fifth value is the number of curves completed. The sixth value is the specific curve to test - it is only used in debugging. The seventh value is 0 for 2^N-1 factoring, 1 for 2^N+1 factoring. The eighth value is the MB of memory the program should use. I don't understand how to set the ECM= paramaters to accomplish my goal. It is my understanding that one can use ECM or 2^p-1 factoring with V19. Any help would be appreciated. Thanks Dan _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: ECM Factoring
I would like to look for a factor of a mersenne prime in a specific area. For example, for a mersenne exponent of say 40,000,000. I want to use the Prime95b program, (v19 I guess), to search for a factor in a specific range from, say, 2^40 to 2^50. I do not understand the ECM factoring instuctions included with Prime95. For this targeted a test, you might want to use trial factoring simply edit to worktodo.ini file adding the following line Factor=a,b Where a is the mersenne exponent, and 2^b is the limit trial factored to. you can override the default trial factoring depth with the line FactorOveride=n where n is the power of 2 that you want it to stop at. (I think that is how it is spelled, see undoc.txt) (a rather ironic title in my opinion) I don't understand how to set the ECM= paramaters to accomplish my goal. It is my understanding that one can use ECM or 2^p-1 factoring with V19. (I think you mean P-1 factoring). Yes, but ECM wouldn't be best for such a targeted search (as I understand it). -Lucas _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: ECM Factoring
When this is cleared up, it will make a good FAQ. Who maintains the FAQ list? Do you agree the answer here is a good FAQ? At 01:10 PM 10/2/99 -0700, you wrote: Hi, I need some help. I would like to look for a factor of a mersenne prime in a specific area. For example, for a mersenne exponent of say 40,000,000. I want to use the Prime95b program, (v19 I guess), to search for a factor in a specific range from, say, 2^40 to 2^50. I do not understand the ECM factoring instuctions included with Prime95. You can also edit the worktodo.ini file directly. For example: ECM=751,300,0,100,0,0,0,24 The first value is the exponent. The second value is bound #1. The third value is bound #2 - leave it as zero. The fourth value is the number of curves to test. The fifth value is the number of curves completed. The sixth value is the specific curve to test - it is only used in debugging. The seventh value is 0 for 2^N-1 factoring, 1 for 2^N+1 factoring. The eighth value is the MB of memory the program should use. I don't understand how to set the ECM= paramaters to accomplish my goal. It is my understanding that one can use ECM or 2^p-1 factoring with V19. Any help would be appreciated. Thanks Dan _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: ECM Factoring
When this is cleared up, it will make a good FAQ. Who maintains the FAQ list? Do you agree the answer here is a good FAQ? I would like to look for a factor of a mersenne prime in a specific area. For example, for a mersenne exponent of say 40,000,000. I want to use the Prime95b program, (v19 I guess), to search for a factor in a specific range from, say, 2^40 to 2^50. I do not understand the ECM factoring instuctions included with Prime95. I maintain the FAQ (well, one of three anyway). There is my FAQ which deals mostly with the math involved with Mersenne numbers. There is Scott's FAQ which deals with primenet, and there is George's FAQ which deals with Prime95. I have gotten questions involving all three (and at least 2 letters which assert mine as the "best"). I like the current separation for a number of reasons: (1) It makes sense (2) I know next to nothing about Prime95, and even less about primenet (3) I don't really care enough about the other two to put forth much effort. (Note that I *do* apreciate Prime95 and primenet, I just don't care much about specific issues with them). Now the last one might sound bad, but with school, I hardly have time to add anything I care about to the FAQ (there is a section on P-1 factoring, Q3.10 BTW). Hopefully this should explain things a bit. I will (eventually, once I read more on it) add a section to the FAQ about ECM, but Prime95 specific issues I know little about, and George would be much better suited to writing about this. Sorry if my rambling makes no sense... Lucas _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Mersenne: ECM Factoring
Glenn Brown writes: The computer has found TWO factors of 2^647+1. It's still searching! WHY Good question. Most likely, because what's left is still composite. But since I don't know what program you're using nor what factors it has found, I can't help you more without more information. From the current lowM.txt file, which presently includes all the data that I have on incompletely factored Mersenne numbers with exponents up to 200,000: M( 1294 )C: 4570409 M( 1294 )C: 9021769 M( 1294 )C: 932184694939 ... since: (2^647 + 1)*(2^647 - 1) = (2^647)^2 - 1^2 = 2^1294 - 1 = M(1294) ... factors of 2^647 + 1 will be listed under M(1294) in lowM.txt. Factors of M(1294) that are also factors of M(647) are only listed under M(647). Data for completely factored Mersenne numbers is moved from lowM.txt to factoredM.txt. LowM.txt - factors, cofactors' primality, etc. - is verified by the ecm3 program of the mers package every time I update my data, usually for all exponents up to around 15,000 (depending on how long I let it run). New data is gathered from George Woltman's ftp site, Paul Leyland's Cunningham Project ftp site, and Conrad Curry's P-1 data ftp site automatically as part of my update scripts. Will http://www.garlic.com/~wedgingt/mersdata.tgz tar'd gzip'd lowM.txt, etc. mersdata.zip DOS zip'd lowM.txt, etc. mersfmt.txtdescription of format mersenne.html descriptions and links
