Mersenne Digest Saturday, October 27 2001 Volume 01 : Number 896 ---------------------------------------------------------------------- Date: Thu, 25 Oct 2001 09:30:50 -0500 From: Tony Pryse Subject: Re: Mersenne: Lucas Wiman Mersenne Prime FAQ Dan, The FAQ is correct. (The version I saw has "10,000,000 exponents" corrected to "10,000,000 digits", as you note it should.) The number of digits, d, in a Mersenne number, 2^n-1, is "the least integer greater than or equal to n/log_2(10)." (The number of digits in an integer must itself be an integer.) Thus, in your examples: 33,219,278/3.321928094887 = 9,999,999.112..... and the least integer greater than or equal to 9,999,999.112..... is 10,000,000, which is then the number of digits in 2^33,219,278-1 . Likewise for 33,219,280/3.321928094887 = 9,999,999.71436166801 and for 33,219,281/3.321928094887 = 10,000,000.01539..... so the number of digits in 2^33,219,281-1 is 10,000,001, which is the least integer greater than or equal to 10,000,000.01539..... Since 33,219,277/3.321928094887 = 9,999,998.811...., the Mersenne number with exponent 33,219,277 has 9,999,999 digits (the least integer greater than or equal to 9,999,998.811...) and thus 33,219,278 is the first Mersenne number with 10,000,000 digits. Tony Pryse At 01:01 AM 10/25/2001 -0500, you wrote: >Forgive my ignorance but; > >In reading the Lucas Wiman Mersenne Prime FAQ I became confused at the Q5.3 >instruction. (see FAQ insert below). > >I want to know how many decimal digits are in a given MP. > >This part of the FAQ does not make sense to me. > >Specifically; > >First off this question seems to ask 10,000,000 exponents. It must mean >10,000,000 digits. > >The answer given below, M33219278, by my calculations, has less than >10,000,000 digits. The questions below ask "How many digits are in a given >Mp?" and "What is the smallest Mp with a given number of digits?" > >The explanation does not seem to answer that question. > >33,219,278/3.321928094887 = 9,999,999.11230167668 and > >33,219,279/3.321928094887 = 9,999,999.41333167235 and > >33,219,280/3.321928094887 = 9,999,999.71436166801 and > >33,219,281/3.321928094887 = 10,000,000.0153916636 > >This number 33,219,281 seems, from the explanation below, to be the first >Mp to have 10,000,000 decimal digits. Can I depend on this? This would seem >to make the answer 33,219,278 the third highest Mp with less than >10,000,000 digits. > >I need a formula that will definitely give the exact number of decimal >digits in a Mp or Mersenne prime Mp. > >Can you help? > >Thanks >Dan > ***************************************************** Kenneth M. (Tony) Pryse Department of Biochemistry and Molecular Biophysics Campus Box 8231 Washington University School of Medicine 660 South Euclid Avenue St. Louis, MO 63110-1093 Tel.: 314-362-3345 Fax: 314-362-7183 ***************************************************** _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 25 Oct 2001 10:31:57 -0500 From: Ken Kriesel Subject: Re: Mersenne: Lucas Wiman Mersenne Prime FAQ At 01:01 AM 10/25/2001 -0500, you wrote: >Forgive my ignorance but; > >In reading the Lucas Wiman Mersenne Prime FAQ I became confused at the Q5.3 >instruction. (see FAQ insert below). > >I want to know how many decimal digits are in a given MP. >This part of the FAQ does not make sense to me. > >Specifically; > >First off this question seems to ask 10,000,000 exponents. It must mean >10,000,000 digits. > >The answer given below, M33219278, by my calculations, has less than >10,000,000 digits. The questions below ask "How many digits are in a given >Mp?" and "What is the smallest Mp with a given number of digits?" > >The explanation does not seem to answer that question. > >33,219,278/3.321928094887 = 9,999,999.11230167668 and > >33,219,279/3.321928094887 = 9,999,999.41333167235 and > >33,219,280/3.321928094887 = 9,999,999.71436166801 and > >33,219,281/3.321928094887 = 10,000,000.0153916636 > >This number 33,219,281 seems, from the explanation below, to be the first >Mp to have 10,000,000 decimal digits. Can I depend on this? This would seem >to make the answer 33,219,278 the third highest Mp with less than >10,000,000 digits. Mp is shorthand for Mersenne Prime, a number having value one less than two raised to the power p where p is a prime, often written in ascii, 2^p-1 meaning (2^p) -1 and not 2^(p-1) because exponentiation is an operator of higher precedence than subtraction. 2^33219278-1 is not a Mersenne Prime since 33219278 is not prime, being even. The only exponent of the four above that is prime is 33219281. (33219279 mod 3 = 0 by eye; 33 21 9 27 9) M33219278 is the smallest Mersenne Number with at least 10^7 digits, but M33219281 is the smallest Mersenne Prime with at least 10^7 digits. This distinction is economically important because >I need a formula that will definitely give the exact number of decimal >digits in a Mp or Mersenne prime Mp. At 09:30 AM 10/25/2001 -0500, Tony Pryse wrote: >Dan, > >The FAQ is correct. (The version I saw has "10,000,000 exponents" corrected >to "10,000,000 digits", as you note it should.) > >The number of digits, d, in a Mersenne number, 2^n-1, is "the least integer >greater than or equal to n/log_2(10)." (The number of digits in an integer >must itself be an integer.) The rule in the FAQ answer misses a case. Consider some very small exponents: 2^0=1; log10(1)=0; # of digits =1 2^0-1=0; log10(Mn)= -infinity?; # of digits=1; rule yields 0 2^1=2; log10(2)=~.3010; 1 digit 2^2=4; log10(4)=~.6020; 1 digit 2^3=8; log10(8)=~.9030; 1 digit 2^4=16; log10(16)=~1.204; 2 digits ... 2^10=1024; log10(1024)=~3.0103; 4 digits 10^1=10; log10(10)=1; 2 digits 10^3=1000; log10(1000)=3; 4 digits The number of digits required is always at least one. The number of digits is rounded up, not down. I suggest the "or equal" is incorrect. Ken _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 25 Oct 2001 17:56:39 +0200 From: "Steinar H. Gunderson" Subject: Mersenne: Re: Lucas Wiman Mersenne Prime FAQ On Thu, Oct 25, 2001 at 10:31:57AM -0500, Ken Kriesel wrote: >M33219281 is the smallest Mersenne Prime with at least 10^7 digits. Possibly "Mersenne prime candidate", not "Mersenne prime"? 33219281 is prime, but my guess is somebody has checked 2^33219281-1 long ago, and I haven't heard of any prime being found there ;-) /* Steinar */ - -- Homepage: http://www.sesse.net/ _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 25 Oct 2001 10:58:03 -0500 From: softmade@mailtag.com Subject: Mersenne: Re:Lucas Wiman Mersenne Prime FAQ THIS MESSAGE WAS ORIGINALLY ADDRESSED TO SIEGMUND@MOSQUITONET.COM AND A CARBON COPY HAS BEEN SENT TO YOU. - ------------------------------------------------------------------------- I noticed the new Faq has been changed from exponents to digits. Also below; - -> - -> Your calculations are fine. Just one slight detail you forgot: - -> - -> 10^2 is the smallest number with *3* digits; - -> 10^3 is the smallest with *4* digits; - -> and so on. - -> - -> INT[ Log10 [ N] + 1 ] always gives the number of digits in N. Here, that - -> is INT [ exponent * log10[2] +1 ], or INT [ exponent / 3.32etc + 1] - -> So INT [ exponent / 3.32etc + 1] = number of decimal digits in 2^exponent-1? Right? The part of the FAQ states: - -> > >we can work similarly to come up with how many digits are in a Mersenne - -> > >number: - -> > - -> > >10^(d-1)-1 < 2^n-1 <= 10^d-1 - -> > >10^(d-1) < 2^n <= 10^d - -> > >log_2(10^(d-1)) < n <= log_2(10^d) - -> > >(d-1)*log_2(10) < n <= d*log_2(10) - -> > >d-1 < n/log_2(10) <= d - -> > - -> > >2^n-1 has d digits. Well 2^127-1 has 39 digits and 127/3.321928094887 = 38.2308094493297819. The above states n/log_2(10) <= d. Does this not mean less than or equal to d? This seems either in error or misleading. I am surprised that this explanation is a answer to the original question of the FAQ which was "How many digits are in a given Mp?". The simple formula; INT [ exponent / 3.321928094887 + 1] = number of decimal digits in 2^exponent-1 would have been more straight forward to us novices. Thanks for your help. Dan _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 25 Oct 2001 12:31:46 -0400 From: Sandy Harris Subject: Re: Mersenne: Lucas Wiman Mersenne Prime FAQ softmade@mailtag.com wrote: > > Forgive my ignorance but; > > In reading the Lucas Wiman Mersenne Prime FAQ I became confused at the Q5.3 > instruction. (see FAQ insert below). > > I want to know how many decimal digits are in a given MP. The FAQ seems to be right about the exact answer, once the exponents/digits typo is fixed. A handy approximation is: 10^3 = 1000 ~= 1024 = 2^10 So ten binary digits are slightly more than three decimal digits. Of course for large numbers, this is fairly innaccurate. 10^300 is quite a bit less than 2^1000, for example. 1.024^100 times less to be exact. _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 25 Oct 2001 14:11:43 EDT From: EWMAYER@aol.com Subject: Mersenne: Mprime crash Last night, one of the 2 mprime jobs I run on my Linux PC at work died. It apprently died due to an illegal sumout error. Now these are quite common, an normally appear in my results.txt file in the form Iteration: 1019208/10199069, ERROR: ILLEGAL SUMOUT Possible hardware failure, consult the readme file. Continuing from last save file. The one last night, OTOH, was of the form ERROR: ILLEGAL SUMOUT Possible hardware failure, consult the readme file. i.e. no iteration number, and no "Continuing from last save file." message following it - it just died at this point. There was also a file write error about 2 hours before the crash, this turned out to be due to a full user partition on my hard drive (which I've since fixed) and I don't know if it has anything to do with the sumout errors (it seemes they should not be related.) Here is the excerpt from the results file - you can see the first file write error on 10/24 around 16:35, then a checksum error at 17:45 which apparently was recovered from OK, then at 18:30 the ILLEGAL SUMOUT error which caused the crash. That is followed on 10/25 (i.e. after I came to work today) by two "FATAL ERROR: Writing to temp file." messages, as I twice tried to restart, before realizing my disk was full. After clearing out a couple hundred MB I again tried to restart at 9:47, but again got a "ERROR: ILLEGAL SUMOUT" message. Has one of my CPUs gone flaky on me? Is it possible that both of the 2 savefiles (they're both there, and both of the proper size) are corrupt? Any help would be welcome, - -Ernst Excerpt from results.txt file: [Wed Oct 24 16:24:51 2001] Iteration 7736000 / 12962641 [Wed Oct 24 16:34:54 2001] Iteration 7738000 / 12962641 Error writing intermediate file: rC962641 [Wed Oct 24 16:45:00 2001] Iteration 7740000 / 12962641 [Wed Oct 24 16:55:04 2001] Iteration 7742000 / 12962641 [Wed Oct 24 17:05:04 2001] Iteration 7744000 / 12962641 [Wed Oct 24 17:15:04 2001] Iteration 7746000 / 12962641 [Wed Oct 24 17:24:59 2001] Iteration 7748000 / 12962641 [Wed Oct 24 17:34:53 2001] Iteration 7750000 / 12962641 [Wed Oct 24 17:44:46 2001] Iteration 7752000 / 12962641 Iteration: 7752549/12962641, ERROR: SUM(INPUTS) != SUM(OUTPUTS), 1524171845291614 != 283103064441664.6 Possible hardware failure, consult the readme file. Continuing from last save file. [Wed Oct 24 18:29:37 2001] ERROR: ILLEGAL SUMOUT Possible hardware failure, consult the readme file. [Thu Oct 25 09:21:07 2001] FATAL ERROR: Writing to temp file. [Thu Oct 25 09:28:29 2001] FATAL ERROR: Writing to temp file. [Thu Oct 25 09:47:40 2001] ERROR: ILLEGAL SUMOUT Possible hardware failure, consult the readme file. _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 25 Oct 2001 16:38:10 -0400 From: George Woltman Subject: Re: Mersenne: Mprime crash Hi Ernst, At 02:11 PM 10/25/2001 -0400, EWMAYER@aol.com wrote: >Last night, one of the 2 mprime jobs I run on my Linux >PC at work died. It apprently died due to an illegal >sumout error. Now these are quite common, an normally >appear in my results.txt file in the form > >Iteration: 1019208/10199069, ERROR: ILLEGAL SUMOUT >Possible hardware failure, consult the readme file. >Continuing from last save file. > >The one last night, OTOH, was of the form > >ERROR: ILLEGAL SUMOUT >Possible hardware failure, consult the readme file. This is weird. FYI: ILLEGAL SUMOUT means the checksum value was an invalid floating point value, such as infinity, NaN, etc. This can be caused by a cpu problem, memory problem, and (at least in Windows 9x) an OS driver not saving the FPU state properly. I would guess Linux would only have the first two causes. >i.e. no iteration number, and no "Continuing from last >save file." message following it - it just died at this >point. Maybe it was doing P-1 factoring??? Have you tried running mprime -d v21 mprime should have finished off the LL test before doing any other work - so I'm a bit baffled here. > There was also a file write error about 2 hours >before the crash, this turned out to be due to a full >user partition on my hard drive (which I've since fixed) >and I don't know if it has anything to do with the >sumout errors (it seemes they should not be related.) I agree they should not be related. >Has one of my CPUs gone flaky on me? My guess is yes (or memory is bad). >Is it possible >that both of the 2 savefiles (they're both there, and >both of the proper size) are corrupt? Yes, but you would see an error message (I think in both results.txt and prime.log) that the pXXXXXXX is bad, renaming qXXXXXXX to pXXXXXXX, and again pXXXXXXX is bad. >Iteration: 7752549/12962641, ERROR: SUM(INPUTS) != SUM(OUTPUTS), >1524171845291614 != 283103064441664.6 This error is real bad - almost always an indicator of a hardware problem. Time for some torture tests. Sorry I cannot be more helpful, George _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 25 Oct 2001 21:29:27 +0000 (GMT) From: Russel Brooks Subject: Mersenne: Quick Stats dropped number of Factors I just noticed this morning that when I went to display my Quick Stats the number field of the Factors has been dropped. I now see: > rlbrooks Rank 926.,92 LL Tests completed, factors found, P90... That use to be: "..completed, 17 factors found, ..." Cheers... Russ _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 25 Oct 2001 22:01:32 -0000 From: bjb@bbhvig.uklinux.net Subject: Re: Mersenne: Lucas Wiman Mersenne Prime FAQ On 25 Oct 2001, at 10:31, Ken Kriesel wrote: > M33219278 is the smallest Mersenne Number with at least 10^7 digits, > but M33219281 is the smallest Mersenne Prime with at least 10^7 > digits. Um, I seem to remember testing that number & confirming Rick Pali's discovery that it is _not_ prime. Perhaps it would be fair to say that M33219281 _was_ the smallest _candidate_ 10 million (decimal) digit Mersenne prime (pending LL testing). It isn't even that now. 33219281 was, is and always will be the smallest _prime_ value of n such that 2^n-1 has at least 10 million (decimal) digits; we know that a Mersenne prime _must_ have a prime exponent, therefore there cannot possibly be a 10 million (decimal) digit Mersenne prime less than M33219281. There are (AFAIK) two status changes left for M33219281: one day (maybe reasonably soon) someone will find a proper factor of this number, and one day (probably decades, centuries or even millenia away) it will be completely factored. Regards Brian Beesley _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Fri, 26 Oct 2001 09:31:15 +0100 From: "David Jaggard" Subject: Re: Mersenne: Mprime crash I've noticed one of the errors in your results file is: > Iteration: 7752549/12962641, ERROR: SUM(INPUTS) != SUM(OUTPUTS), 1524171845291614 != 283103064441664.6 This is a definite hardware failure. If the PC is overclocked then you probably need to increase the core or i/o voltage or reduce the speed. If its not overclocked then try swapping out the memory or the CPU. Of course if your hardware has failed in some way it won't come as a suprise that your PC does other wierd things, like Mprime crashing... The fact that you say errors are common suggests your PC has always had some problems. My work PC never shows any errors and after a bit of tweaking my overclocked PC at home never shows any errors. Mprime is a pretty good health test. At a long shot you might try removing any non-essential devices to check its not a driver problem. Presumably a badly written Linux driver can cause the same problems as a badly written Windows driver. Ideally you don't want any errors at all. If you're getting errors as commonly as you say then the accuracy of your results will be questionable. Because of double-checking this won't be a problem for the group but its going to be a bit of a waste of time for you. - ----- Original Message ----- From: To: Cc: Sent: Thursday, October 25, 2001 7:11 PM Subject: Mersenne: Mprime crash > Last night, one of the 2 mprime jobs I run on my Linux > PC at work died. It apprently died due to an illegal > sumout error. Now these are quite common, an normally > appear in my results.txt file in the form > > Iteration: 1019208/10199069, ERROR: ILLEGAL SUMOUT > Possible hardware failure, consult the readme file. > Continuing from last save file. > > The one last night, OTOH, was of the form > > ERROR: ILLEGAL SUMOUT > Possible hardware failure, consult the readme file. > > i.e. no iteration number, and no "Continuing from last > save file." message following it - it just died at this > point. There was also a file write error about 2 hours > before the crash, this turned out to be due to a full > user partition on my hard drive (which I've since fixed) > and I don't know if it has anything to do with the > sumout errors (it seemes they should not be related.) > > Here is the excerpt from the results file - you can see > the first file write error on 10/24 around 16:35, then a > checksum error at 17:45 which apparently was recovered > from OK, then at 18:30 the ILLEGAL SUMOUT error which > caused the crash. That is followed on 10/25 (i.e. after > I came to work today) by two "FATAL ERROR: Writing to temp file." messages, as I twice tried to restart, > before realizing my disk was full. After clearing out > a couple hundred MB I again tried to restart at 9:47, > but again got a "ERROR: ILLEGAL SUMOUT" message. > > Has one of my CPUs gone flaky on me? Is it possible > that both of the 2 savefiles (they're both there, and > both of the proper size) are corrupt? > > Any help would be welcome, > > -Ernst > > Excerpt from results.txt file: > > [Wed Oct 24 16:24:51 2001] > Iteration 7736000 / 12962641 > [Wed Oct 24 16:34:54 2001] > Iteration 7738000 / 12962641 > Error writing intermediate file: rC962641 > [Wed Oct 24 16:45:00 2001] > Iteration 7740000 / 12962641 > [Wed Oct 24 16:55:04 2001] > Iteration 7742000 / 12962641 > [Wed Oct 24 17:05:04 2001] > Iteration 7744000 / 12962641 > [Wed Oct 24 17:15:04 2001] > Iteration 7746000 / 12962641 > [Wed Oct 24 17:24:59 2001] > Iteration 7748000 / 12962641 > [Wed Oct 24 17:34:53 2001] > Iteration 7750000 / 12962641 > [Wed Oct 24 17:44:46 2001] > Iteration 7752000 / 12962641 > Iteration: 7752549/12962641, ERROR: SUM(INPUTS) != SUM(OUTPUTS), 1524171845291614 != 283103064441664.6 > Possible hardware failure, consult the readme file. > Continuing from last save file. > [Wed Oct 24 18:29:37 2001] > ERROR: ILLEGAL SUMOUT > Possible hardware failure, consult the readme file. > [Thu Oct 25 09:21:07 2001] > FATAL ERROR: Writing to temp file. > [Thu Oct 25 09:28:29 2001] > FATAL ERROR: Writing to temp file. > [Thu Oct 25 09:47:40 2001] > ERROR: ILLEGAL SUMOUT > Possible hardware failure, consult the readme file. > > > _________________________________________________________________________ > 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 ------------------------------ Date: Fri, 26 Oct 2001 11:36:35 -0400 From: Nathan Russell Subject: Re: Mersenne: Mprime crash On Fri, 26 Oct 2001 09:31:15 +0100, "David Jaggard" wrote: >Presumably a badly written Linux driver >can cause the same problems as a badly written Windows driver. IIRC, Linux drivers that are kernel modules do run in real mode; someone on the list please correct me if I'm wrong. This raises the question of why some folks have mentioned that drivers under NT/2K don't cause these sorts of problems.... Nathan _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Fri, 26 Oct 2001 11:25:36 -0500 From: Ken Kriesel Subject: Re: Mersenne: Lucas Wiman Mersenne Prime FAQ At 10:01 PM 10/25/2001 -0000, bjb@bbhvig.uklinux.net wrote: >On 25 Oct 2001, at 10:31, Ken Kriesel wrote: > >> M33219278 is the smallest Mersenne Number with at least 10^7 digits, >> but M33219281 is the smallest Mersenne Prime with at least 10^7 >> digits. > >Um, I seem to remember testing that number & confirming Rick >Pali's discovery that it is _not_ prime. > >Perhaps it would be fair to say that M33219281 _was_ the smallest >_candidate_ 10 million (decimal) digit Mersenne prime (pending LL >testing). It isn't even that now. As Steinar Gunderson promptly pointed out, I should have said not "Mersenne Prime" but something like "Mersenne Prime Candidate". That would be valid until at least one LL test completes giving nonprime result, after which I would consider it a probable nonprime. After a matching double check completes, I think most would regard it a proven nonprime. Brian's double check completed April 6 on M33219281, confirming Rick Pali's results of Nov 5 2000; this exponent was tested as part of the QA effort and was for a time the largest completed double check. (M40250087 is to my knowledge the largest completed single or double-check.) How about this: M33219281 is the smallest Mersenne Number of prime exponent with at least 10^7 digits. Currently there is no Mersenne Prime known with 10^7 or more digits, so my error yesterday is rather glaring. Oops. Ken _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Fri, 26 Oct 2001 19:13:56 -0400 From: George Woltman Subject: Mersenne: Fwd: Re: ECM testing From Phil Moore, who cannot join the Mersenne mailing list right now because Luke Welsh's scruznet.com ISP went under. Luke will host his mailing list sign up page when he has some free time. >Date: Fri, 26 Oct 2001 14:43:17 -0700 >From: "Phil Moore" >Subject: ECM testing > > From time to time, I see letters on this list asking if there is still > valuable work to be done with older, slower computers. If you would like > an alternative to factoring and double-checking assignments, I suggest > ECM (Elliptic Curve Method) testing. For one thing, you already have the > Prime95 (or mprime) software in your computer. For another, ECM curves > on small numbers run relatively quickly. Two projects on the web-pages at: >www.mersenne.org/ecm.htm really could benefit from additional computers. > >1) The smallest numbers on the Cunningham lists 2^N+1 and 2^N-1 will >become future condidates for factoring by the SNFS (Special Number Field >Sieve) method. Already, M673 and P647 are on the Cunningham list of the >"10 most wanted numbers"; see: >http://www.cerias.purdue.edu/homes/ssw/cun/third/index.html >(Also, P653, P659, and P661 are on the list of "more wanted numbers".) >SNFS requires enormous computer resources, and the people doing this don't >want to waste those resources if these numbers might have 45 or 50 digit >factors which could be more easily found by ECM. So usually, some major >ECM effort precedes SNFS work. In addition, there is a small, but >non-zero chance (maybe one in a million?) that running one curve at >B1=44,000,000 on one of these numbers could find a record-sized ECM factor >of >55 digits! > >2) The second project I would like to recommend is ECM factoring of Fermat >numbers. I have been working on this for over 2 years without success, >but I still think that the average computer's chance of finding a Fermat >factor is considerably higher than finding a Mersenne prime. The last >Fermat factor found by ECM was the factor of F18 discovered in April 1999, >but I would estimate that there are probably 2 or 3 additional Fermat >factors within reach of Prime95. The work involved scales roughly as (# >of digits)^0.2, so that finding a 40-digit factor takes roughly 10 times >the amount of work needed to find a 35-digit factor. So running 19,300 >curves at B1=44,000,000 to look for 50-digit factors of the 14th Fermat >number P16384 would take around 175 years on a 400 MHz Pentium II, while >running the 10,300 curves at B1=11,000,000 for 45-digit factors would only >take 20 or so years. More time has been spent on the numbers F14, F20, >and F22 which have no known factors, but I notice that the Fermat numbers >F17, F19, and F21 have had relatively less searching. > >So if you have a computer which will work for electricity, download the >lowm.txt and lowp.txt files into your Prime95 folder and start >searching! You can always run one curve just to see how long it >takes. Small exponents should only take a couple of hours. I have run >curves which took about a week each on F23 on 400 MHz Pentium II's running >Windows 98 with 128M of memory, but if you decide to work on these large >numbers, depending on what else you are running, you may have to >experiment with the memory allocation in the main menu to find an optimum >setting. Good luck! > >Phil Moore >Lane Community College >Eugene, Oregon _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Fri, 26 Oct 2001 21:29:47 EDT From: RSNFLD@aol.com Subject: Mersenne: Re: Mersenne Digest V1 #895 - --part1_35.1ce89028.290b680b_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Hi group This question was asked before but I lost the info. What is the website to obtain a copy of WINTOP, the memory usage program. Also, what is the site for the archives of this list. Please answer this directly to me. Thanks Irv Rosenfeld - --part1_35.1ce89028.290b680b_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: 7bit Hi group

This question was asked before but I lost the info.  What is the website to obtain a copy of  WINTOP, the memory usage program.  Also, what is the site for the archives of this list.

Please answer this directly to me.

Thanks
Irv Rosenfeld - --part1_35.1ce89028.290b680b_boundary-- _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sat, 27 Oct 2001 08:46:26 +0100 From: Gareth Randall Subject: Re: Mersenne: Re: Mersenne Digest V1 #895 It's actually a Microsoft program and is one of their "kernel toys" package. http://www.microsoft.com/windows95/downloads/contents/wutoys/w95kerneltoy/ I'll answer to the group as well since this is a very useful tool for prime95 users. It allows you to spot processes that go into busy waits and the like which waste CPU time. Try holding the mouse button down on the desktop - went to 100% CPU on my Win95 system, but I haven't used that in over a year now! RSNFLD@aol.com wrote: > > Hi group > > This question was asked before but I lost the info. What is the website to obtain a copy of WINTOP, the memory usage program. Also, what is the site for the archives of this list. > > Please answer this directly to me. > > Thanks > Irv Rosenfeld - -- ======= Gareth Randall ======= _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sat, 27 Oct 2001 09:59:32 +0200 From: Lars Lindley Subject: Mersenne: 3 years Hey everybody! Yesterday (friday 26th) it was three years since I joined the search! It's been fun! My team is Account ID LL P90* Exponents Fact.P90 Exponents P90 CPU CPU yrs LL Tested CPU yrs* w/ Factor hrs/day - -------------- ------- --------- -------- --------- ------- Team_LiTH 122.875 492 4.112 38 1013.12 and right now we are at place 70 in the top producers! We are using 25 machines of all types. K6-2, Athlon, PI, PII, PIII. I recently retired my old 486. It was doing one factorisation every 3-4 months or so... Now me and another teammember will go out and celebrate :) I just wanted to say KEEP UP THE FUN WORK! :) Regards, /Lars "Feeder of FPU's" Lindley _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sat, 27 Oct 2001 10:34:25 -0400 From: Jud McCranie Subject: Re: Mersenne: Re: Mersenne Digest V1 #895 At 08:46 AM 10/27/2001 +0100, Gareth Randall wrote: >I'll answer to the group as well since this is a very useful tool for >prime95 users. Yes, it is great. On Windows XP ctrl-alt-del shows that information (maybe on Win 2000 too). However, WinTop puts blanks for zero percentages whereas ctrl-alt-del on WinXP shows 00. It doesn't even omit the leading zero. +---------------------------------------------------------+ | Jud McCranie | | | | Programming Achieved with Structure, Clarity, And Logic | +---------------------------------------------------------+ _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ End of Mersenne Digest V1 #896 ******************************