mersenneforum.org Factoring 43rd Term of Euclid-Mullin sequence
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 2005-02-02, 03:31 #23 grandpascorpion     Jan 2005 Transdniestr 503 Posts 150 more for a total of 4700 at B1=11M
2005-02-03, 08:12   #24
ValerieVonck

Mar 2004
Belgium

5×132 Posts

Quote:
 Originally Posted by grandpascorpion Cedric, Does the input indicate it ran 200 curves? The input file needs to be in Unix format. I bumped into this problem myself. Folks, I'll try to close out the B1=11000000 factoring

To be honest: I do not know this.
I have put my concerns into the software section of the mersenneforum.
I have also tried to read everything on ecm what I could find.
I never found any complete tutorial, example.

Best of luck with your factoring project.

Regards
Cedric Vonck

 2005-02-03, 09:04 #25 patrik     "Patrik Johansson" Aug 2002 Uppsala, Sweden 52×17 Posts Normal output could (if you don't find any factors) look like: Code: GMP-ECM 5.0.3 [powered by GMP 4.1.4] [ECM] Input number is 2784908410762794071887414394815651793559267258537102016323316206 42982062389901741890579963524423782637435949041666525000702723914662388812510545 494307250950777886431051612811386531 (180 digits) Using B1=11000000, B2=25577181640, polynomial Dickson(12), sigma=1058443219 Step 1 took 338410ms Step 2 took 231680ms Run 2 out of 1000: Using B1=11000000, B2=25577181640, polynomial Dickson(12), sigma=762516686 Step 1 took 338160ms Step 2 took 233180ms Run 3 out of 1000: [---] Run 999 out of 1000: Using B1=11000000, B2=25577181640, polynomial Dickson(12), sigma=252573442 Step 1 took 334870ms Step 2 took 230990ms Run 1000 out of 1000: Using B1=11000000, B2=25577181640, polynomial Dickson(12), sigma=2738065587 Step 1 took 334500ms Step 2 took 231170ms Finding a factor (for another number, of course) could look like this: Code: Step 2 took 85320ms ********** Factor found in step 2: 310280425886984887694911580049011296782214691 8598407 Found probable prime factor of 52 digits: 31028042588698488769491158004901129678 22146918598407 Composite cofactor 2115042966390179978303718113827180116042610311426696576586244 13023205204173795594453958188167116829523236801468161403289317068522085489 has 1 35 digits Last fiddled with by patrik on 2005-02-03 at 09:05
 2005-02-03, 09:22 #26 ValerieVonck     Mar 2004 Belgium 11010011012 Posts Never saw this before.... my batch file look like this: ecm5 11e6 25577181640 -c 100 -save save.txt -resume resume.txt < factor.txt factor.txt contains the factor. I stripped the CR (carriage return) Nothing more nothing less.
 2005-02-03, 11:12 #27 akruppa     "Nancy" Aug 2002 Alexandria 2,467 Posts Command line options such as -c, -save etc must be placed before the B1, B2 values. Gmp-ecm stops parsing the command line after B2. The options -save and -resume have no meaning for what you're trying to do anyways, you can use them to do part of stage 1 now and the rest later, or import stage 1 residues from other programs. Since you want to do complete curves in one go, you don't really want saving or resuming of residues. Alex
2005-02-03, 12:47   #28
ValerieVonck

Mar 2004
Belgium

34D16 Posts

Quote:
 Originally Posted by akruppa Command line options such as -c, -save etc must be placed before the B1, B2 values. Gmp-ecm stops parsing the command line after B2. The options -save and -resume have no meaning for what you're trying to do anyways, you can use them to do part of stage 1 now and the rest later, or import stage 1 residues from other programs. Since you want to do complete curves in one go, you don't really want saving or resuming of residues. Alex
So my _exact_ syntax should be:

ecm5 -c 100 11e6 25577181640 < factor.txt
?????

2005-02-03, 13:13   #29
patrik

"Patrik Johansson"
Aug 2002
Uppsala, Sweden

1101010012 Posts

Quote:
 Originally Posted by CedricVonck So my _exact_ syntax should be: ecm5 -c 100 11e6 25577181640 < factor.txt ?????
Yes, except that you could skip 25577181640, since that is the default value. If you want to save your output in a file you could type:

ecm5 -c 100 11e6 < factor.txt > out.txt

I don't know how the -c option works when you find a factor. Does it stop then? Otherwise your found factor could scroll above the top of the window if you don't send the output to a file. (Earlier I have only used gmp-ecm on numbers of the form 2^n-1, where Prime95 is faster for step 1, and then I don't have to use -c when I run step 2 using gmp-ecm. That is an example of a case when -resume is used.)

2005-02-03, 14:21   #30
akruppa

"Nancy"
Aug 2002
Alexandria

2,467 Posts

Quote:
 Originally Posted by patrik I don't know how the -c option works when you find a factor. Does it stop then?
It stops if the cofactor is a probable prime, but continues working on composite cofactors.

Alex

 2005-02-03, 20:28 #31 ValerieVonck     Mar 2004 Belgium 5·132 Posts Will try.... Sorry guys, problem remains. I leaving this "factoring" project..... Good results... Last fiddled with by ValerieVonck on 2005-02-03 at 20:39
 2005-02-07, 18:26 #32 patrik     "Patrik Johansson" Aug 2002 Uppsala, Sweden 52·17 Posts 800 curves with B1=43e6, default B2 (=178426462988). I have one more idea that might explain how ecm behaved for CedricVonck, and that is if LF or CR LF is missing completely in factor.txt. (Both these two works for me.) I.e. if the size is 180 bytes it won't work. The size should be 181 or 182 bytes for this 180 digit factor. Windows notepad works a bit different regarding this compared to e.g. the UNIX program vi. In notepad, if you type a line without hitting return in the end, no CR LF will be appended, but in vi you get a LF. If you do hit return and the end of a notepad line you will get CR LF, while in vi you then would get two lines (terminated with LF). Last fiddled with by patrik on 2005-02-07 at 18:28
 2005-02-07, 19:56 #33 Mystwalker     Jul 2004 Potsdam, Germany 14778 Posts I also had some hard time figuring it out. Here is comes: command line: ecm5 -c 100 43e6 < factor.txt factor.txt has to contain the factor, followed by a \n Then, you have to start a new line (inside the file). Now it works for me... Last fiddled with by Mystwalker on 2005-02-07 at 20:04

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