Mersenne Digest Monday, June 19 2000 Volume 01 : Number 749 ---------------------------------------------------------------------- Date: Sat, 17 Jun 2000 17:54:08 EDT From: "Nathan Russell" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Factoring Assignments: Are They Always "First-Time?" >From: Jeff Woods <[EMAIL PROTECTED]> >To: [EMAIL PROTECTED] >Subject: Re: Mersenne: Factoring Assignments: Are They Always >"First-Time?" >Date: Sat, 17 Jun 2000 17:14:00 -0400 > >At 01:00 PM 6/17/00 -0700, you wrote: (snip) >>If a factor is >>found for an exponent, it's eliminated from further testing >>of any kind. > >Isn't the factor itself verified? I would assume it is, however verifying a factor takes well under a P-90 second. Nathan ________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sat, 17 Jun 2000 23:19:15 +0200 From: Lem Novantotto <[EMAIL PROTECTED]> Subject: Re: Mersenne: LOST NUMBERS On Sat, 17 Jun 2000 17:28:52 +0200 (CEST), in Mersenne_mailing_list you wrote: >On Sat, 17 Jun 2000, Lem Novantotto wrote: >> Hi! >> I think it would be nice to post the mersenne numbers you're still >> working to, and that have been reassigned, so, hopefully, the new >> tester can read them and stop his testing. Otherwise HE is going to >> loose time and credit. >Since first and double checks are credited equally(as far as I know), >both should get credited with the same amount of work except for counting >tests. Yes. But I'm saying is that, in my experience, if you send a LL_first_checking result after someone else, your test isn't considered a double checking... astonishing enough, it isn't considered at all. Otherwise, how do you explain what happened to me? See my post in reply to: Mersenne: assignment 'stolen' a few posts ago. - -- Bye. Lem - ---------- 'CLOCK is what you make of it' ---------- _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sat, 17 Jun 2000 15:23:04 -0700 From: Spike Jones <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: Pointers on farming Michael Bell wrote: > ...back to your 37pence/MHz figure. Also note memory prices have gone up, so > 32M now costs about �40-50!! Maybe this is the first time in recent history > the price of a computer has stabilised?? Hmm, dont think so. I was over at Fry's electronics this morning. The 400 MHz machines like the one I paid 2400 bucks for less than 2 yrs ago with the same amount of memory was selling for 300 bucks. Which I think is about 200 pounds? The 2000-2300 dollar machines are all 1 Ghz now. Computer prices look to me to be as much in freefall as ever. spike _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sat, 17 Jun 2000 20:14:04 +0100 From: "Siegmar Szlavik" <[EMAIL PROTECTED]> Subject: Re: Mersenne: LOST NUMBERS On Sat, 17 Jun 2000 17:28:52 +0200 (CEST), Henrik Olsen wrote: >On Sat, 17 Jun 2000, Lem Novantotto wrote: >> On Sat, 17 Jun 2000 05:37:06 -0400, in Mersenne_mailing_list you >> wrote: >> >Is all your hard work(and subsequent credit) lost? No, although the server >> >has already re-assigned them to another account it will still accept the >> >results and properly credit your account for the completed work. >> Hi! >> I think it would be nice to post the mersenne numbers you're still >> working to, and that have been reassigned, so, hopefully, the new >> tester can read them and stop his testing. Otherwise HE is going to >> loose time and credit. >Since first and double checks are credited equally(as far as I know), >both should get credited with the same amount of work except for counting >tests. >Time spent on a doublecheck is only wasted if it's turned into a >triplecheck and all three results agree. > Yes, but they are testing in the 10-million-digit range, so it is not only a question of time and credit. I think it would be just fair to inform the new testers that they are doing in fact just a doublecheck and let them decide if they want to continue under these circumstances or take another 'fresh' exponent. Siegmar _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 18 Jun 2000 05:40:42 +0700 (ICT) From: Warut Roonguthai <[EMAIL PROTECTED]> Subject: Re: Mersenne: Pointers on farming On Sat, 17 Jun 2000, Michael Bell wrote: > Warning on K6's: As far as GIMPS is concerned they're not too good, because > the FPU is about half the speed of the Intel Pentium FPU. (If you run RC5 > then they're as good, if not better, because they have very good integer > units). K6 is not good at RC5 either; see http://www.pcbenchmarks.com/distribu.htm I've heard that RC5 requires some kind of rotate function that is hardwired on Intel processors but not on K6 and Alpha. _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sat, 17 Jun 2000 16:09:32 -0700 From: Eric Hahn <[EMAIL PROTECTED]> Subject: Re: Mersenne: Factoring Assignments: Are They Always "First-Time?" Jeff Woods wrote: >>being found. Currently, all exponents thru Prime95's limit of >>79.3M have been factored to at least 2^50... If a factor is >>found for an exponent, it's eliminated from further testing >>of any kind. > >Isn't the factor itself verified? Yes, it is. However, at least in the case of Prime95, George has written the code such that the factor is validated before it's even displayed as a being a factor and written to the results file. If it's invalid, the code continues as if the "factor" was never found... Eric _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sat, 17 Jun 2000 21:56:09 EDT From: [EMAIL PROTECTED] Subject: Mersenne: Re: Mersenne Digest V1 #748 <<Willamette(s) which is supposed to debut at 1.4GHz...>> Remind me what a Willamette is again. All I know about are Merced (I mean, Itanium), and the second-generation Itanium called McKinley. STL _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sat, 17 Jun 2000 22:50:04 EDT From: [EMAIL PROTECTED] Subject: Mersenne: Prime64? Will Prime95 be rewritten to run on the Itanium, when it comes out? Seems to me like 64-bit operation will speed it up significantly, as will the insane amount of registers and floating point units and all the other microprocessor whatnot that I'm not current on. A review (thanks, Stefan Struiker!) of the Itanium mentions, "The CPU will then switch to 32-bit mode on the fly and carry on as if it were a more powerful PIII or Willamette. This all happens because the Itanium supports the IA-32 instructions natively.... All software has to be rewritten to take advantage of the IA-64 architecture." So Prime95 will run on an Itanium, but a "Prime64" might be even better and wickedly faster. With what I'm learning about programming, it seems that more registers are always a good thing, especially for memory-intensive processes. STL _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sat, 17 Jun 2000 20:17:22 -0700 From: "John R Pierce" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: Mersenne Digest V1 #748 Williamette is the next-generation x86 architecture machine. It has (will have) a way accelerated CPU clock and even more instructions execute in fewer clocks, but it has a deeper pipeline and increased instruction latency. First generation Williamettes are supposedly going to debut around 1.2GHz and go up from there. It also has more and better onchip cache, both L1 and L2. I believe it has some major structural changes to the PPro/P2/P3 style bus, requiring completely new chipsets. - -jrp - ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Saturday, June 17, 2000 6:56 PM Subject: Mersenne: Re: Mersenne Digest V1 #748 > <<Willamette(s) which is supposed to debut at 1.4GHz...>> > > Remind me what a Willamette is again. All I know about are Merced (I mean, > Itanium), and the second-generation Itanium called McKinley. > > STL > _________________________________________________________________ > 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: Sat, 17 Jun 2000 20:27:01 -0700 From: Stefan Struiker <[EMAIL PROTECTED]> Subject: Mersenne: Linux And The Slippery Gnome TeamG: Trying to start a PrimeHunt on a Linux box, but can't find the Gnome switch/requeste(o)r to get the screen resolution down enough so I can read without a microscope. Can anyone help? Am running Redhat 6.1 with a VooDoo 3500 GFX card. So until last year I thought Linux was a cartoon character. Leave and learn.. Best Wishes, Stefanovic _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 18 Jun 2000 01:27:40 -0400 (EDT) From: Jason Stratos Papadopoulos <[EMAIL PROTECTED]> Subject: Re: Mersenne: Prime64? On Sat, 17 Jun 2000 [EMAIL PROTECTED] wrote: > Will Prime95 be rewritten to run on the Itanium, when it comes out? Seems to > me like 64-bit operation will speed it up significantly, as will the insane > amount of registers and floating point units and all the other > microprocessor > whatnot that I'm not current on. Intel has had documentation available on the Web for a while that details the architecture of Itanium. If Prime95 is ever rewritten for IA64 it would have to be not only a total rewrite but a complete rethinking of the FFTs it uses. For example, integer multiply-adds take only a little longer than floating point multiply-adds; should IA64Prime use an integer or floating point FFT? If integer, there are big delays in shuffling between integer and FPU registers (only the FPU can multiply). If floating point, loads and stores will all take longer, the cache behavior is totally different, and the arrays involved get longer because you can't pack bits as densely as an integer solution. Itanium can do two FPU operations per clock, but both can be multiply-adds instead of just multiplies or adds. Can you rearrange a real-valued FFT to use multiply-adds as much as possible? It could cut the operation count in half if you do, but to my knowledge no one has yet done so. It's been done for complex FFTs, but Prime95 really wants real-valued FFTs, not complex ones. Moving to IA64 will be a much bigger challenge than simply rewriting half a meg of assembly language. jasonp _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 18 Jun 2000 04:39:47 -0700 From: Paul Leyland <[EMAIL PROTECTED]> Subject: RE: Mersenne: Factoring with ECM > From: Yann Forget [mailto:[EMAIL PROTECTED]] > Could you explain this to me ? I can try. The text below is deliberately informal in style and far from mathematically rigorous. The mathematicians on the list will have to forgive me; those who want a more rigorous explanation should be able to find one with relative ease. > I am factoring Fermat numbers with ECM. > Is this relevant in this case ? It is relevant for all numbers, but only when ECM produces a composite factor. To be honest, your chance of finding even one unknown factor of a Fermat number with ECM is tiny, and your chances of finding two or more *on the same curve* are somewhere between nil and negligible. > Paul Leyland said: > As long as the coefficients of the curve and the starting point are > recorded, we can re-run exactly the same computation, with the small primes > curtailed as in the p-1 case, on the same curve and the number c. It's > because my software doesn't normally output the curve and starting point > used that the idea hadn't occurred to me. Ok, what's happening with ECM is that we are performing arithmetic not with ordinary integers but with points on an elliptic curve --- a polynomial of the form y^2 = ax^3+b. (Actually, we are calculating with integers, but in a complicated manner which corresponds to manipulating points on a polynomial). The "starting point" I mentioned is a point which lies on the curve and, with a few special exceptions, it doesn't matter too much which point is chosen. When the arithmetic is performed modulo a composite number, there are a finite number of points on the curve. Each different curve will, in general, have a different number of points. When the number of points on a particular curve is divisible *only* by primes less than the first stage limit B1, with perhaps at most one prime larger than B1 but smaller than the 2nd stage limit B2, ECM will find a corresponding factor. Usually this factor will be a prime, but occasionally it will be the product of two or more primes. Each of these primes corresponds to a different selection of small primes smaller than B1 and, usually, only one will correspond to the prime larger than B1 and smaller than B2. If you then repeat the calculation, using exactly the same curve and starting point but with a reduced set of primes <B1 and/or omit the one >B1, the factor which corresponds to the omitted primes *won't* be discovered, thereby revealing the other. Paul _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 18 Jun 2000 11:23:53 +0200 From: Lem Novantotto <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: Mersenne Digest V1 #748 On Sat, 17 Jun 2000 21:56:09 EDT, in Mersenne_mailing_list you wrote: >Remind me what a Willamette is again. All I know about are Merced (I mean, >Itanium), and the second-generation Itanium called McKinley. Hi! If you are interested in differences between willamette and mustang, try this (a bit technical): http://www.chip-architect.com/mw.pdf - -- Bye. Lem - ---------- 'CLOCK is what you make of it' ---------- _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 18 Jun 2000 10:44:41 -0700 From: Bob Margulies <[EMAIL PROTECTED]> Subject: Mersenne: New DSL connection The DSL modem on my Windows 98 PC works beautifully. But now when Prime95 tries to contact the server, I get the message Dial-up connection not active. Will try contacting server again in 2 minutes. What do I need to do? _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 18 Jun 2000 13:13:56 -0700 From: Will Edgington <[EMAIL PROTECTED]> Subject: Mersenne: Linux And The Slippery Gnome Trying to start a PrimeHunt on a Linux box, but can't find the Gnome switch/requeste(o)r to get the screen resolution down enough so I can read without a microscope. Can anyone help? Am running Redhat 6.1 with a VooDoo 3500 GFX card. Presuming you're running in an xterm window, try holding down a control key and pressing & holding your third mouse button while in that window; xterm should bring up a list of font sizes. Simply release the mouse button while the mouse cursor is on the one that you want to try. This means that each xterm can have a different font size, if that's what you want. The font, including size, can also be given on the command line, as in 'xterm -fn 9x15bold' (e.g.). 'xlsfonts' will list the fonts your X11 server knows about, but it's usually a very long list, so you probably want to redirect it into a file ('xlsfonts > file') or something similar ('xlsfonts | more', perhaps). Setting the font you want so that new xterms start with it is somewhat messy, usually involving your ~/.Xdefaults file, but there may be a configuration tool in Gnome that I'm not aware of (I was using X11 before Linux was created, let alone before Gnome, so ... :). Some X11 configurations, usually declared in /etc/X11/XF86Config, support more than one video resolution, which is usually changed while running X with control-alt-(keypad's + key) and control-alt-(keypad -). These support virtual screens in that the pixels that fit within the display area are only part of what X11 is actually displaying; simply try to move the mouse off the edge of the screen towards what you want to see that's off the edge. The size of the virtual screen is only limited by the amount of memory your video card can access and the color depth (256 colors fit in 8 bits, e.g., as Mersenne hunters should know :). Will http://www.garlic.com/~wedgingt/mersenne.html _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 18 Jun 2000 13:58:59 -0700 From: Will Edgington <[EMAIL PROTECTED]> Subject: Mersenne: Factoring Assignments: Are They Always "First-Time?" Stefan Struiker writes: When a requested factoring assignment is listed with, say, 52 in an account log, does this mean it has been factored to 52 bits, but _without_ success? Yes, the number should have no factors less than 2^52. Or could a factor have already been found in some cases, but less than 52 bits long? Nope, unless the factor was not reported for some reason (bug, disk crash, etc.). My strategy in factoring 13.3 mill exponents and up, is to save L-L testing and DCing time by knocking some out early. Seem to be on a roll, too, with factors found 40% of the time, with a turnaround of 40 hours per. That's a very high rate of factors, I'd've thought, but that happens sometimes. In any case, Prime95 "knows" how much factoring work should be done for a particular Mersenne number before starting an LL test (first or double-check) on it and will do more factoring if the data it gets from Primenet (or other source) indicates the number has not been factored "enough". The predicated chances of finding a factor during trial and P-1 factoring is taken into account, along with how long the factoring takes to do and how long the two LL tests will take. So your phrase "knocking some out early" is exactly correct: if noone tries to factor a particular Mersenne number before it is given to a Prime95 that wants to run an LL test, that Prime95 will do some factoring first, usually before it even finishes the prior Mersenne number's LL test (to make sure it has "enough" work in worktodo.ini). Eric Hahn writes: If it's listed as 52 in the fact-bits column of the report, it means that it's been trial-factored thru 2^52 without any factors being found. Currently, all exponents thru Prime95's limit of 79.3M have been factored to at least 2^50... If a factor is found for an exponent, it's eliminated from further testing of any kind. Yup. Here's a short summary of my current data. For Mersenne numbers with prime exponent that have no LL test nor a factor, here are the smallest exponents trial factored only as far as the last column: M( 5178743 )U: 2^62 M( 8896813 )U: 2^61 M( 9993539 )U: 2^60 M( 10078559 )U: 2^55 M( 11300657 )U: 2^54 M( 11505331 )U: 2^53 M( 11521879 )U: 2^52 M( 20500019 )U: 2^51 M( 30100181 )U: 2^50 M( 79300037 )U: 2^45 M( 79306169 )U: 2^43 The exponents above 79.3 million have probably only been worked on by me, personally, since they're above Prime95's limit, but I'm still a bit surprised they haven't been factored further; trial factoring to the same depth is _easier_ for larger exponents, not harder. Jeff Woods writes: Isn't the factor itself verified? Yes, if only by me, as I noted in another thread in the last couple of weeks. Will http://www.garlic.com/~wedgingt/mersenne.html _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 18 Jun 2000 15:22:01 +0200 From: "Steinar H. Gunderson" <[EMAIL PROTECTED]> Subject: Mersenne: Re: Pointers on farming On Sun, Jun 18, 2000 at 05:40:42AM +0700, Warut Roonguthai wrote: >K6 is not good at RC5 either; see http://www.pcbenchmarks.com/distribu.htm >I've heard that RC5 requires some kind of rotate function that is >hardwired on Intel processors but not on K6 and Alpha. But K6 is quite OK at factoring, since there is a special integer version of factoring in Prime95. /* Steinar */ - -- Homepage: http://members.xoom.com/sneeze/ _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 18 Jun 2000 22:41:24 -0000 From: "Brian J. Beesley" <[EMAIL PROTECTED]> Subject: Re: Mersenne: LOST NUMBERS On 17 Jun 00, at 23:19, Lem Novantotto wrote: > >Since first and double checks are credited equally(as far as I know), > >both should get credited with the same amount of work except for counting > >tests. > > Yes. But I'm saying is that, in my experience, if you send a > LL_first_checking result after someone else, your test isn't considered > a double checking... astonishing enough, it isn't considered at all. AFAIK PrimeNet will record the result of the second test - though it may not be obvious from the reports - and you won't get the CPU time credit for it. The result will work its way into the database (look in lucas_v.txt) & will be credited in George's list (which also includes manually submitted results). Regards Brian Beesley _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 18 Jun 2000 19:54:07 -0400 From: "Vincent J. Mooney Jr." <[EMAIL PROTECTED]> Subject: Re: Mersenne: Prime64? I met George Woltman in Orlando, Florida a week ago and as I recall, he agreed that (as you said, Jason) "If Prime95 is ever rewritten for IA64 it would have to be not only a total rewrite but a complete rethinking of the FFTs it uses." George is up to the task, happily. At 01:27 AM 6/18/00 -0400, Jason Papad wrote: > > >On Sat, 17 Jun 2000 [EMAIL PROTECTED] wrote: > >> Will Prime95 be rewritten to run on the Itanium, when it comes out? Seems to >> me like 64-bit operation will speed it up significantly, as will the insane >> amount of registers and floating point units and all the other >> microprocessor >> whatnot that I'm not current on. > >Intel has had documentation available on the Web for a while that details >the architecture of Itanium. If Prime95 is ever rewritten for IA64 it >would have to be not only a total rewrite but a complete rethinking of >the FFTs it uses. For example, integer multiply-adds take only a little >longer than floating point multiply-adds; should IA64Prime use an integer >or floating point FFT? If integer, there are big delays in shuffling >between integer and FPU registers (only the FPU can multiply). If floating >point, loads and stores will all take longer, the cache behavior is >totally different, and the arrays involved get longer because you can't >pack bits as densely as an integer solution. > >Itanium can do two FPU operations per clock, but both can be multiply-adds >instead of just multiplies or adds. Can you rearrange a real-valued FFT >to use multiply-adds as much as possible? It could cut the operation count >in half if you do, but to my knowledge no one has yet done so. It's been >done for complex FFTs, but Prime95 really wants real-valued FFTs, not >complex ones. > >Moving to IA64 will be a much bigger challenge than simply rewriting >half a meg of assembly language. > >jasonp > > >_________________________________________________________________ >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: Sun, 18 Jun 2000 20:15:33 -0400 From: "Vincent J. Mooney Jr." <[EMAIL PROTECTED]> Subject: Re: Mersenne: Factoring Thanks for the factor.exe citation. At 01:40 AM 6/16/00 -0700, Jim Howell wrote: >[Wed 14 Jun 2000, Paul Leyland writes] > >Today I found this number 3756482676803749223044867243823 with ECM and >B1=10,000. It has two factors, each of 16 digits, which could *not* have >been found by trial division in any reasonable time. > >------------- > >I use a program called "factor.exe", which uses several factoring methods. It factors the above number within several seconds. (For this number, the factors are found with the P-1 method.) In case anyone is interested, the factors are 1483398061194277 and 2532349728015299. > >This program runs on Windows, and can be downloaded from Chris Caldwell's main page, at: > >http://www.utm.edu/research/primes > >Go down to section 4, (Software), and look for "factor.exe", described as a DOS program, but it actually runs in a Command Window on Windows 95 and later, and (probably) not under actual DOS. I find "factor.exe" quite useful for factoring small numbers (it will accept numbers up to about 130 digits). >--Jim > ><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> ><HTML><HEAD> ><META content="text/html; charset=iso-8859-1" http-equiv=Content-Type> ><META content="MSHTML 5.00.2314.1000" name=GENERATOR> ><STYLE></STYLE> ></HEAD> ><BODY bgColor=#ffffff> ><DIV><FONT face=Arial size=2>[Wed 14 Jun 2000, Paul Leyland writes]</FONT></DIV> ><DIV><FONT face=Arial size=2><BR>Today I found this number >3756482676803749223044867243823 with ECM and<BR>B1=10,000. It has two >factors, each of 16 digits, which could *not* have<BR>been found by trial >division in any reasonable time.</FONT></DIV> ><DIV><FONT face=Arial size=2></FONT> </DIV> ><DIV><FONT face=Arial size=2>-------------</FONT></DIV> ><DIV><FONT face=Arial size=2></FONT> </DIV> ><DIV><FONT face=Arial size=2>I use a program called "factor.exe", which uses >several factoring methods. It factors the above number within several >seconds. (For this number, the factors are found with the P-1 >method.) In case anyone is interested, the factors are >1483398061194277 and 2532349728015299.<BR></FONT></DIV> ><DIV><FONT face=Arial size=2>This program runs on Windows, and can be downloaded >from Chris Caldwell's main page, at:</FONT></DIV> ><DIV><FONT face=Arial size=2></FONT> </DIV> ><DIV><FONT face=Arial size=2><A >href="http://www.utm.edu/research/primes">http://www.utm.edu/research/prime s</A></FONT></DIV> ><DIV><FONT face=Arial size=2></FONT> </DIV> ><DIV><FONT face=Arial size=2>Go down to section 4, (Software), and look for >"factor.exe", described as a DOS program, but it actually runs in a Command >Window on Windows 95 and later, and (probably) not under actual DOS. I >find "factor.exe" quite useful for factoring small numbers (it will accept >numbers up to about 130 digits).</FONT></DIV> ><DIV><FONT face=Arial size=2>--Jim</FONT></DIV> ><DIV><FONT face=Arial size=2> </DIV></FONT></BODY></HTML> > _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 18 Jun 2000 17:40:09 -0700 From: "Pardoe, Richard (PRDR)" <[EMAIL PROTECTED]> Subject: RE: Mersenne: New DSL connection Open the Prime95 window Select Test - PrimeNet Remove the check mark before "Use a dial-up connection to the Internet" From: Bob Margulies >The DSL modem on my Windows 98 PC works beautifully. But now when >Prime95 tries to contact the server, I get the message > >Dial-up connection not active. >Will try contacting server again in 2 minutes. > >What do I need to do? _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 18 Jun 2000 21:25:11 -0400 From: "Larry Murray" <[EMAIL PROTECTED]> Subject: Mersenne: LOST NUMBERS I thought had occurred to me with this prize that is being offered. what happens if you work on a number for 6 months and then it is re-assigned to a person with a faster computer and their computer finishes the computation first and it is found to be a prime. Who is entitled to the Prize? Does that mean if you have A slower 550mhz computer don't bother testing a 10 million number? If you do make sure you always check in because it can be taken from you? On the same subject what-if you're the person the number is reassigned to and you work on a number for 6 months to find that it was a reassignment and it was found to be prime...I think with the longer testing time of the 10 million digit numbers the time between reassignment of those numbers should be much longer. I personally have been running 3 ten million digit numbers on Pentium 550's since September of 1999 and hardly ever even bother with the computers that are running them I have strictly devoted them to the mersenne project...ANYWAY ITS SOMETHING TO THINK ABOUT--TAKE CARE ALL _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 19 Jun 2000 13:21:13 -0000 From: "Brian J. Beesley" <[EMAIL PROTECTED]> Subject: Re: Mersenne: LOST NUMBERS On 18 Jun 00, at 21:25, Larry Murray wrote: > I thought had occurred to me with this prize that is being offered. what > happens if you work on a number for 6 months and then it is re-assigned to > a person with a faster computer and their computer finishes the > computation first and it is found to be a prime. Who is entitled to the > Prize? Does that mean if you have A slower 550mhz computer don't bother > testing a 10 million number? If you do make sure you always check in > because it can be taken from you? On the same subject what-if you're the > person the number is reassigned to and you work on a number for 6 > months to find that it was a reassignment and it was found to be > prime...I think with the longer testing time of the 10 million digit > numbers the time between reassignment of those numbers should be much > longer. I personally have been running 3 ten million digit numbers on > Pentium 550's since September of 1999 and hardly > ever even bother with the computers that are running them I have strictly > devoted them to the mersenne project...ANYWAY ITS SOMETHING TO THINK > ABOUT--TAKE CARE ALL You have to check in occasionally to keep the assignment. This is entirely reasonable since some people are bound to "default" without bothering to return the assignment. If it's too inconvenient to connect the actual systems to allow them to check in, you can use the PrimeNet Manual Testing page to check assignments in manually in order to prevent them from expiring. Since you can "extend" an assignment for up to 120 days (plus the 60 day grace period) you should only need to do this two or three times during the run. If you run assignments which aren't given to you by PrimeNet, or continue to work on assignments which have been reallocated due to your failure to check them in occasionally, I don't think you should be entitled to a share of any prize. However it looks as though, according to the EFF rules (which I haven't looked at for a while), the first discovery reported to EFF takes precedence. Since the expected return on testing numbers in the 10 million digit range is of the order of 40 cents / PIII-550 year, I doubt too many people are participating simply because of the existence of the prize ... ? Also, note that it's entirely possible that the EFF prize will be won by someone working on non-Mersenne numbers using entirely different software and/or hardware. BTW for QA reasons I am already working on a double-check of a 10 million digit number before the first test is completed. I will make damn sure that the "official" owner of the assignment reports the final result, abandons or allows the assignment to expire before I report the result myself. (And the "official" owner knew this before I started!) Personally, and bearing in mind that there are a lot of much smaller exponents which still require testing, I consider a standard PC running a PIII-550 to be inadequate for running 10 million digit exponents. I'm using an Athlon 650, which is about 35% faster, and I have a system (self-)built for reliability rather than down to a price. However, GOOD LUCK to all those who do chance their arm! Regards Brian Beesley _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 19 Jun 2000 13:21:13 -0000 From: "Brian J. Beesley" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Prime64? On 18 Jun 00, at 1:27, Jason Stratos Papadopoulos wrote: > For example, integer multiply-adds take only a little longer > than floating point multiply-adds; should IA64Prime use an integer or > floating point FFT? If integer, there are big delays in shuffling between > integer and FPU registers (only the FPU can multiply). If floating point, > loads and stores will all take longer, the cache behavior is totally > different, and the arrays involved get longer because you can't pack bits > as densely as an integer solution. This obviously needs to be looked at & evaluated on real hardware. > > Itanium can do two FPU operations per clock, but both can be multiply-adds > instead of just multiplies or adds. Can you rearrange a real-valued FFT to > use multiply-adds as much as possible? It could cut the operation count in > half if you do, but to my knowledge no one has yet done so. Yes, but you get only about 40% saving - you need about 10 additions for every 6 multiplications. "No-one has bothered" because the effort is pointless on IA32 architecture processors, and there simply aren't enough processors which have an efficient "a*b+c" instruction around to make it worthwhile to put in the required programming effort. (What goes around, comes around. The VAX architecture - very, very CISC - had three-operand instructions, but the trend to RISC systems made such things unfashionable. Now hardware designers are realizing that we need such things for performance reasons!) > Moving to IA64 will be a much bigger challenge than simply rewriting > half a meg of assembly language. I wonder whether we will get better performance running IA32 software or using a HLL program like Mlucas in native IA64 mode? Depends to a large extent on the availability & performance of optimizing compilers, I suppose. Regards Brian Beesley _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 19 Jun 2000 20:43:11 +0200 From: Guillermo Ballester Valor <[EMAIL PROTECTED]> Subject: Mersenne: New Lucas-Lehmer test program. Hi to all: In the last weeks I've been writing a program to perform l-l test. I'm the guy who wrote an adaptation of MacLucasUNIX to FFTW package half year ago. It seemed to run fast on intelx86 but in other platforms the Mlucas and MacLucasUNIX was better than MacLucasFFTW. I had learnt from that the first thing I must to made was to write my own FFT code. I did it, and the code seems to be fast. I called it YEAFFT (Yet Another FFT) and actually is a fast convolver. It is a complex based FFT and uses intensively the C-macro expansion facilities. The FFT routines are based in a short file of macros which includes all the common tasks. This macros now are written in a generic form but I suppose they can be tuned for a particular target, even more it can be replaced by assembler code if our C-compiler supports this feature. My aim when writing the code was that it could run I a the big variety of systems. In fact, my test version (without priority management) runs in a old 486 pc with Borland turbo c++ under MSdos 6-20, and also runs on Alpha 21264 . With the -Dmacro compiler flags one can choose a lot of features of the package to adjust it to the target system and made it as fast as possible. Ernst W. Mayer kindly has made some timings and has created a telnet count for me in his machines. Without his suggestions and help in testing I've not been able to write this code. The results are similar to Mlucas on MIPS and Alpha's. It can be a good new for those platforms without a f90 compiler but good C ones (for example Apple Mac. users). It supports the same FFT lengths than prime95 plus a radix-9 (like Mlucas). The Lucas-Lehmer test code, which calls to YEAFFT routines is called Glucas. The code runs fine on my pentium 166-MMX under SuSE Linux (about 50% of performance than mprime, but better than MacLucasFFTW). The I/O code is from Will Edgington MERS package. Now Will Edgington is working to include it in his MERS release, and hope soon we will have results. For test proposes there is other program, ylucas2, with the same interface than original Dr. Crandall lucdwt.c (it has not restart features nor priority management and then not recommended for a complete big l-l test) but is good to see the possibilities of Glucas. I can send a zip copy of the source to interested people. Send me a private e-mail. Soon there will be other L-L tester in the GIMPS arena. I wonder whether there will be a 'universal' interface to primenet, (perhaps in Java), able to read the outputs from Mlucas, MacLcasUNIX, Glucas ... dialog with primenet server and manage the tasks to do by with the clients, all in automatic form (no manual). Regards. Guillermo. _________________________________________________________________ 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 #749 ******************************
