Mersenne Digest Monday, May 14 2001 Volume 01 : Number 851 ---------------------------------------------------------------------- Date: Mon, 14 May 2001 16:14:07 -0400 From: "Joshua Zelinsky" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: 26 exponents Nathan Russel wrote: >Are you suggesting that, every time George offers exponents to the >members of this mailing list, he should send out a newsletter to every >participant - guaranteeing hundreds or thousands of replies for him to >deal with? I think there may be no good solution to this. Have the e-mails go to an account linked to the server. It would take a little work, but the whole process could be automated. Regards, Joshua Zelinsky [EMAIL PROTECTED] _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 20:23:45 -0000 From: "Brian J. Beesley" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: 26 exponents On 14 May 2001, at 8:45, Nathan Russell wrote: > >First of all, as Jud notes, the 'elitism' is already there, in that different > >machines get treated differently in the assignments that they are given. Sorry, I don't buy that. Every system has exactly the same chance of picking up any given assignment; it's a matter of the time at which you make the request. And you _can_ override the assignment type which would be the default for your system, if you wish to do so. > > >Even readers of this list > >get opportunities to acquire exponents or prebeta-test software, etc., that > >are not available to the unwashed masses. AFAIK everyone is entitled to subscribe to this list, whether they participate by running assignments or not. > > Additionally, GIMPS, > unlike most other projects, has exponents taht are 'better' than > others. In the absence of completed tests, small exponents are more likely to be prime than larger ones, as well as taking less effort to test. However, note that a considerable number of users have voluntarily chosen to run 10 million digit range exponents, thus reducing the probability that they will discover a prime. The increased reward for being successful counterbalances the reduced chance of success. There is also a theoretical difference between those exponents congruent to 1 modulo 4 and those congruent to 3 modulo 4. However I believe that this is due to the fact that one of these groups has a larger probability of having a small factor; thus this irregularity is removed by the time that LL testing begins. > >Secondly, if - when I ask the server to give me "whatever kind of work makes > >most sense" - it gives me something else, whether out of spurious concern for > >my feelings or for any other reason, then not only are the programmers > >betraying my trust in them, they are also indicating that they don't trust me > >to ask for what I want. I agree. Either you allow people to choose the type of work they want, or you tell people plainly that you will select for them the type of work you will ask them to do. Either works, but a mixture is inconsistent. > > Note that an exponent given out for triple-checking has a microscopic > chance of being prime (something like two in one billion), since it > must > > 1. Be prime (once chance in 60,000-70,000) and > 2. Have been missed by both previous tests (1 in 100 for each). NO! Conditional probability: if we need a third LL test run, it is because at least one of the other two _must_ be in error. So the probability of finding a prime on the third LL test run is (about) one half the probability of finding a prime on the second LL test run - - irrespective of the error rate, provided it is small. > > >People need to be informed about > >departures from documented practice. > > Are you suggesting that, every time George offers exponents to the > members of this mailing list, he should send out a newsletter to every > participant - guaranteeing hundreds or thousands of replies for him to > deal with? I think there may be no good solution to this. Clearly this is ridiculous. I don't have a problem with George offerring a few exponents "selectively" through this list, because the list does not have a closed membership. The only sane alternative is to wait for "deadline critical" assignments to complete in the normal way - something which some people have vociferously objected to. 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, 14 May 2001 20:23:45 -0000 From: "Brian J. Beesley" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Pentium 4 owners - pre-beta prime95 release available On 14 May 2001, at 9:08, George Woltman wrote: > At 01:02 AM 5/14/2001 -0700, xqrpa wrote: > >Is ordinary factoring code also present ("Factor Only") and is > >there a corresponding speed-up? > > The factoring code is present but unchanged. Thus, no speedup. ... except for the fact that the slowest P4 processor runs about as fast as the fastest Athlon, and is also supposed to be more efficient at executing integer instructions. Trial factoring seems to be well in advance of LL testing, so it probably doesn't matter too much. But is there any scope for using SSE2, or even MMX / 3DNow, extensions in trial factoring? The point being that trial factoring can be implemented reasonably efficiently as almost pure integer code. If we could test two or four factors in parallel, we should get a considerable speedup, even though some of the "threads" would spend some time "stalled" whilst exceptions were dealt with in another. 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, 14 May 2001 13:29:55 -0700 From: "Aaron Blosser" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Emails and virus (slightly OT) :) > > I'll try to keep this a little bit on-topic... Does this mailing list do > > any sort of virus scanning? I know you can't post to the list unless you're > > actually on the list, but any scanning going on? > > No there isn't any virus scanning going on. > > There is however a message limit that tends to block most attachments. > > FWIW, I work at Postini, http://www.postini.com , a company that provides > real time email spam and virus blocking services. Customers simply point > their MX records at us, and then we take care of the rest, filtering > stuff out, and passing on just the good mail. I don't however run base.com > mail through Postini. base.com provides me a portal on the net without the > Postini filters in place. This is useful for collecting spam which can > then be used to tune Postini's spam filtering engine. I was just wondering... that Homepage virus that was going around last week was actually relatively small. I don't know what size limits you have on the list, but it did cross my mind: what would happen if someone got a virus and had [EMAIL PROTECTED] in their address book (as I do). As for blocking spam, I created a spam user and try to advertise that as much as possible, hoping it'll get on as many lists as there are. The email software we use, Communigate, will reject any email that has that spamtrap user as one of the recipients. Works fine for those spammers that use to: or cc: fields, but not really much help for the bcc. Oh well. I wonder... could the base.com be setup to block all attachments, or, for that matter, block HTML posts, allowing text only? Aaron (who is currently fighting off some spam of his own... grid.net user bouncing off mindspring.net and then into our machines... argh!) _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 13:34:24 -0700 From: "Aaron Blosser" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Emails and virus (slightly OT) :) > >Sorry, I just felt the urge to say this. There is nothing particualarily > >bad about Outlook Express, these various viruses require you to excute > >attachments, and you can do that in any mail client.. > > Not true! With Outlook Express all you have to do is read the message. > The virus can be embedded in the message with Outlook Express. The > "Wscript.KakWorm" virus is a particularly bad example of this. > For details see: > > http://www.sarc.com/avcenter/venc/data/wscript.kakworm.html Well, that's true if you haven't upgraded your IE with the latest security patches, and especially true if you're security zones are left at the default which allow all sorts of nonsense to go on. Call me paranoid ("Hey, paranoid!"), but setting your security zones in IE to be more restrictive is absolutely vital. I'm puzzled as to why older versions of IE were so lax. I haven't tried it, but my co-workers who are more daring have said that the IE6 beta actually does a better job of restricting your sites more, so the Internet site allows less monkey-business. The Kakworm, fortunately, never made it "big time", but you're right, that was a fine example of an HTML email actually being able to cause some damage. One can only ponder what would have happened had it spread better. Aaron _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 14:00:02 -0700 From: "Aaron Blosser" <[EMAIL PROTECTED]> Subject: Overriding assigned exponent type (was Re: Mersenne: Re: 26 exponents) > > >Secondly, if - when I ask the server to give me "whatever kind of work makes > > >most sense" - it gives me something else, whether out of spurious concern for > > >my feelings or for any other reason, then not only are the programmers > > >betraying my trust in them, they are also indicating that they don't trust me > > >to ask for what I want. > > I agree. Either you allow people to choose the type of work they > want, or you tell people plainly that you will select for them the > type of work you will ask them to do. Either works, but a mixture is > inconsistent. I'm confused... I know there's the option to have Primenet "request whatever type of work makes the most sense", or you can uncheck that and select a particular type. That works fine. However, if you do select multiple options, the server will still select which, from among those options, is most suitable for your machine. Personally, I'd always wondered why it let you select multiple types when the point was to override any server "default" and get the type you want. It should be a radio box instead of a combo box on that one, near as I can figure. <...> > Clearly this is ridiculous. I don't have a problem with George > offerring a few exponents "selectively" through this list, because > the list does not have a closed membership. The only sane alternative > is to wait for "deadline critical" assignments to complete in the > normal way - something which some people have vociferously objected > to. Agreed with that, Brian. Besides, people on this list are probably more interested in what's going on than the fellow who just likes knowing that his computer is doing something with all those spare cycles. So offering limited "cool" things to list subscribers is fine by me. Perhaps there could be an option somewhere in the "user information" (same place you set your email address) that would allow you to "opt in" to the mailing list? I fear that many folks may not be aware of the list, or find that subscribing seems too hard (odd as that may sound to us experts :) Next time they're online, it'll update their computer info, generate a subscribe letter for that email address, and they'd still have to respond to the subscribe message, but it's a heckuva lot easier for some people that way. Of course, it would require Scott to do something on Primenet to allow such an option to be trackable, and to generate the subscribe messages to the list. But I reckon you'd see the list membership jump up quite a bit if only it was easier for folks to subscribe. Aaron _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 23:38:24 +0100 From: "Thomas Womack" <[EMAIL PROTECTED]> Subject: Mersenne: Purpose of the self-test; also, aren't P4s fast! I've just collected the beta of version 21, to run on my P4 at home. When I run it on my K62/333 laptop (which I was using as a portable disc having downloaded the beta at college), the self-test tries to test M5242881 with a 256k FFT, gives an excess-roundoff-error message and dies; this is presumably a bug. I did set the processor type to K6. When I run it on the P4, the self-test checks a set of thirty or so exponents with a 320k FFT length, and then does it again, and again, until it's run a total of 306 tests. This surprised me slightly; I was expecting it to exercise all the FFT lengths with random exponents to check for edge-conditions in the new P4 code. Is the self-test in fact just to check that there's not something in the CPU which goes glitchy when running flat-out SSE2 code for hours on end? The P4's PSU fan seems to step up a gear when I've been running Prime95 for a few hours, though the CPU temperature reported by Intel Active Monitor on my D850GB board doesn't go about 46C. I suspect the P4 probably runs too hot for it to be possible to build a really quiet solution, but does anyone have suggestions? In its current state I'd get no sleep if I left the machine running overnight, so I'll probably be running Prime95 only if I remember to set it going when I wake up. 33M ticks per iteration for M5171311, which is 25.8 milliseconds on this 1300MHz machine; so one double-check in that range every 36 hours. That's about a factor six faster than the P2/350 I just sold, and I recall that machine as having been at least four times faster than the P90 I had when I started running Prime95 ... I'll have done noticeably more calculation by the end of next month than that P90 did during its lifetime. Tom _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 17:58:36 -0500 From: "Griffith, Shaun" <[EMAIL PROTECTED]> Subject: re: Mersenne: missing exponents? On 14 May 2001, at 19:04, Brian J. Beesley wrote: > There is already a mechanism where people can opt in or out of being > notified if an assignment is due to expire. There is? At the risk of looking dim, what is it? - -Shaun _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 17:54:14 -0500 From: "Griffith, Shaun" <[EMAIL PROTECTED]> Subject: Mersenne: List Archives (revisited) On Jan 15, 2001, I wrote: > Are the list archives still kept somewhere? to which Siegmar responded: >have a look at http://www.egroups.com/group/mprime :) Since then, Egroups has moved to Yahoo! There are only 6 posts archived after this! Where have the recent archives gone? - -Shaun _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 16:41:36 -0700 From: "Aaron Blosser" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Purpose of the self-test; also, aren't P4s fast! > The P4's PSU fan seems to step up a gear when I've been running Prime95 for > a few hours, though the CPU temperature reported by Intel Active Monitor on > my D850GB board doesn't go about 46C. I suspect the P4 probably runs too hot > for it to be possible to build a really quiet solution, but does anyone have > suggestions? In its current state I'd get no sleep if I left the machine > running overnight, so I'll probably be running Prime95 only if I remember to > set it going when I wake up. Any machine that has a variable speed fan will probably have this same thing happen. On a couple newer Compaq Proliant servers (which have temperature sensitive fans), it's very obvious to tell when I've started the Prime service, because the fans nearly instantly speed up and are noisier. This is, of course, because normally the CPU is pretty idle, not generating much heat at all. But when the service starts, the FPU is suddenly in full time use, and the core generates more heat, which causes the temp switch to notice this, and causes the fans to speed up to dissipate the extra heat. Hearing your fans kick into high gear is a good sign... it means your system is working as intended. :) I'm thankful that most of my servers are off in an air-conditioned room down the hall a bit. It was a real pain when I had a Proliant cluster in my office undergoing some testing, and having those fans spin at full tilt. And if you've ever been around a Proliant server, you'll know what I mean because those things have about a million different fans in them. > 33M ticks per iteration for M5171311, which is 25.8 milliseconds on this > 1300MHz machine; so one double-check in that range every 36 hours. That's > about a factor six faster than the P2/350 I just sold, and I recall that > machine as having been at least four times faster than the P90 I had when I > started running Prime95 ... I'll have done noticeably more calculation by > the end of next month than that P90 did during its lifetime. Hmm... your P4 at 1.3GHz should, on face value, be 3.8 times faster, and according to George, you should be seeing an extra 3 times improvement in the P4 execution for an overall boost (over a P2/350) of over 11 times. Of course, that's assuming similar cache architecture, bus speeds, etc. which we know isn't the case. In fact, without the new code, I'd expect a P4 1300 to be more than 3.8 times faster than P2/350, just on the basis of the memory architecture, FSB (and thus memory) speeds, etc. I assume your beta has been configured with the proper CPU type? Aaron _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 17:27:19 -0700 From: "Aaron Blosser" <[EMAIL PROTECTED]> Subject: Re: Mersenne: missing exponents? > On 14 May 2001, at 19:04, Brian J. Beesley wrote: > > There is already a mechanism where people can opt in or out of being > > notified if an assignment is due to expire. > > There is? At the risk of looking dim, what is it? In the "user information" config window, you enter your email address and there's a checkbox to "receive email from Primenet server if exponents are about to expire". _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 20:52:30 -0400 From: George Woltman <[EMAIL PROTECTED]> Subject: Re: Mersenne: Purpose of the self-test; also, aren't P4s fast! Hi, At 11:38 PM 5/14/2001 +0100, Thomas Womack wrote: >When I run it on my K62/333 laptop, the self-test tries to test M5242881 >with a 256k FFT, gives an excess-roundoff-error message and dies; this is >presumably a bug. Yes, apparently I broke the old FFT code.... Another good reason for only P4 users to download this version! >When I run it on the P4, the self-test checks a set of thirty or so >exponents with a 320k FFT length, and then does it again, and again, until >it's run a total of 306 tests. This surprised me slightly; I was expecting >it to exercise all the FFT lengths with random exponents to check for >edge-conditions in the new P4 code. The SSE2 instructions only support 53 bits of precision. The old Intel FPU supports 64 bits of precision. Consequently, the old FFT code can handle slightly higher exponents. For a 256K FFT, the old code could handle up to 5,250,000, the new code can only handle up to 5,140,000. >Is the self-test in fact just to check >that there's not something in the CPU which goes glitchy when running >flat-out SSE2 code for hours on end? Yes. The QA suite that Ken Kriesel and Brian Beesley worked on does a better job at testing edge conditions. Of course, they'll need to update that suite using the new limits. Regards, George _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 21:06:30 -0400 From: George Woltman <[EMAIL PROTECTED]> Subject: Re: Mersenne: Purpose of the self-test; also, aren't P4s fast! Hi, At 04:41 PM 5/14/2001 -0700, Aaron Blosser wrote: > > That's about a factor six faster than the P2/350 I just sold, > >Hmm... your P4 at 1.3GHz should, on face value, be 3.8 times faster, and >according to George, you should be seeing an extra 3 times improvement in >the P4 execution for an overall boost (over a P2/350) of over 11 times. Not quite, the old FFT code did not run well on the P4. Thus, his 1.3GHz P4 was not 3.8 times faster than his P2/350. - -- George _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 21:05:07 -0400 From: Nathan Russell <[EMAIL PROTECTED]> Subject: Re: Mersenne: missing exponents? On Mon, 14 May 2001 17:27:19 -0700, Aaron Blosser wrote: >> On 14 May 2001, at 19:04, Brian J. Beesley wrote: >> > There is already a mechanism where people can opt in or out of being >> > notified if an assignment is due to expire. >> >> There is? At the risk of looking dim, what is it? > >In the "user information" config window, you enter your email address and >there's a checkbox to "receive email from Primenet server if exponents are >about to expire". I can't find this in my copy (Prime95 20.6.1). Nathan _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 18:17:10 -0700 From: "Aaron Blosser" <[EMAIL PROTECTED]> Subject: Re: Mersenne: missing exponents? Hmm... well, then again, I'm looking at the NTPrime. I've only got one machine running Prime95, and it's been so long... I thought it had all the same options though, but I could just be terribly mistaken. Running NTSetup (part of the NT service package), I show version 20.6.5... Aaron - ----- Original Message ----- On Mon, 14 May 2001 17:27:19 -0700, Aaron Blosser wrote: >> On 14 May 2001, at 19:04, Brian J. Beesley wrote: >> > There is already a mechanism where people can opt in or out of being >> > notified if an assignment is due to expire. >> >> There is? At the risk of looking dim, what is it? > >In the "user information" config window, you enter your email address and >there's a checkbox to "receive email from Primenet server if exponents are >about to expire". I can't find this in my copy (Prime95 20.6.1). Nathan _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 21:44:37 -0400 From: Nathan Russell <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: 26 exponents On Sat, 12 May 2001 16:04:17 -0400, Jud McCranie wrote: >At 03:26 PM 5/12/2001 -0400, Nathan Russell wrote: >I think that's more of a 'quick fix', and might make new participants >>feel that GIMPS doesn't trust them. > >Yes, but a new user need not know that they don't get an exponent that has >expired until they have finished an assignment. My point is that if an >exponent is dropped, it could be reassigned to someone that has shown a >willingness to finish it. However, that is still drawing a distinction between new and experienced users. For that matter, if a milestone is delayed by a month or two, it doesn't significantly hurt everyone's overall odds of finding a prime. >I've been steadily working on GIMPS for nearly 5 years, always 1 fulltime >machine, occasionally 2. I've been doing doublechecks in the 6,000,000 >range for a few months because I use a 300 MHz machine. I know >doublechecking is important. But then I see these few gaps under M38? and >I think "I could have done several of those." I can empathize with you here. However, I was a new user only a little over a year ago, and if someone had said on the mailing list at that time that new users should be given assignments chosen so that they couldn't harm milestones, I would have been upset. Yes, it would be nice to say that we know for sure which Mersenne prime is the thirty-eighth, but doing so does not speed us towards discovering the thirty-ninth. For that matter, I am sure that there are users who have run a single exponent and then left, though they may not be as many as those who left without ever finishing any exponents. Nathan _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 21:56:46 -0400 From: Nathan Russell <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: 26 exponents On Mon, 14 May 2001 20:23:45 -0000, Brian J. Beesley wrote: >On 14 May 2001, at 8:45, Nathan Russell wrote: > >> >First of all, as Jud notes, the 'elitism' is already there, in that different >> >machines get treated differently in the assignments that they are given. (To clarify, I did not write the above - Daran did) > >Sorry, I don't buy that. Every system has exactly the same chance of >picking up any given assignment; it's a matter of the time at which >you make the request. And you _can_ override the assignment type >which would be the default for your system, if you wish to do so. That is indeed true. I would have to say that having defaults different for different systems is a Good Thing; otherwise, you might have someone using a 486 suddenly realize that their computer was doing a first-time check that would take over a year, get frustrated, and give up. >> >> >Even readers of this list >> >get opportunities to acquire exponents or prebeta-test software, etc., that >> >are not available to the unwashed masses. > >AFAIK everyone is entitled to subscribe to this list, whether they >participate by running assignments or not. Agreed. Membership to the list indicates a slightly-more-than-casual interest in the project, specifically a willingness to sift through a few dozen messages per month in order to learn more about the project. That interest might well also be a sign of someone who is more likely to faithfully complete 'special' assignments in a relatively timely fashion. >> >> Additionally, GIMPS, >> unlike most other projects, has exponents taht are 'better' than >> others. > >In the absence of completed tests, small exponents are more likely to >be prime than larger ones, as well as taking less effort to test. >However, note that a considerable number of users have voluntarily >chosen to run 10 million digit range exponents, thus reducing the >probability that they will discover a prime. The increased reward for >being successful counterbalances the reduced chance of success. True - and probably by a greater margin now that ordinary first-time testing is getting higher (12,200,000 now as opposed to 9,700,000 when I joined late in January 2000). >There is also a theoretical difference between those exponents >congruent to 1 modulo 4 and those congruent to 3 modulo 4. However I >believe that this is due to the fact that one of these groups has a >larger probability of having a small factor; thus this irregularity >is removed by the time that LL testing begins. I think I read something similiar. Might it relate to whether the first potential factor itself is prime, specifically whether it is divisible by 3? I can't do the arithmetic in my head, but I have a hunch... > >> >Secondly, if - when I ask the server to give me "whatever kind of work makes >> >most sense" - it gives me something else, whether out of spurious concern for >> >my feelings or for any other reason, then not only are the programmers >> >betraying my trust in them, they are also indicating that they don't trust me >> >to ask for what I want. > >I agree. Either you allow people to choose the type of work they >want, or you tell people plainly that you will select for them the >type of work you will ask them to do. Either works, but a mixture is >inconsistent. Perhaps clicking the 'give me the work that makes the most sense' box should immediately set the appearance of the others to the work that will be chosen, rather than simply graying them out. >> >> Note that an exponent given out for triple-checking has a microscopic >> chance of being prime (something like two in one billion), since it >> must >> >> 1. Be prime (once chance in 60,000-70,000) and >> 2. Have been missed by both previous tests (1 in 100 for each). > >NO! Conditional probability: if we need a third LL test run, it is >because at least one of the other two _must_ be in error. So the >probability of finding a prime on the third LL test run is (about) >one half the probability of finding a prime on the second LL test run >- irrespective of the error rate, provided it is small. I stand corrected here. Nathan Russell _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 22:00:07 -0400 From: Nathan Russell <[EMAIL PROTECTED]> Subject: Re: Mersenne: missing exponents? On Mon, 14 May 2001 18:17:10 -0700, Aaron Blosser wrote: >Hmm... well, then again, I'm looking at the NTPrime. I've only got one >machine running Prime95, and it's been so long... > >I thought it had all the same options though, but I could just be terribly >mistaken. > >Running NTSetup (part of the NT service package), I show version 20.6.5... > >Aaron I have version 20.6.1 - and the web page reads that all versions were last updated June 15 2000. Something odd is going on... Nathan _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 22:46:30 -0400 From: Jud McCranie <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: 26 exponents At 08:23 PM 5/14/2001 +0000, Brian J. Beesley wrote: >On 14 May 2001, at 8:45, Nathan Russell wrote: > > > >First of all, as Jud notes, the 'elitism' is already there, in that > different > > >machines get treated differently in the assignments that they are given. > >Sorry, I don't buy that. Every system has exactly the same chance of >picking up any given assignment; it's a matter of the time at which >you make the request. Under your proposal, exponents would be double assigned. A 200 MHz system and a 1.2 GHz system calling in at about the same time could get the same exponent. But the one with the elite fast system would in effect get the first LL test and the non-elite system would get the DC. Also, if you have a 200 MHz and a 1200 MHz working on the same exponent, if it turns out to be a new prime the 1200 will show that first. Then someone with a fast machine will run a DC before the 200 machine can finish it. I know you said that the 200 still gets credit, but if a prime is reported, we don't want to wait several (possibly many) more months for a DC. Under my proposal, newcomers would get a first time LL test - they just wouldn't get an exponent that someone else had abandoned. That is not to keep newcomers from contributing - they even get to do first time LL tests (and be assured of that) - it is try to keep an exponent from being abandoned more than once. +------------------------------------+ | Jud McCranie | | | | former temporary part-time adjunct | | instructor of a minor university | +------------------------------------+ _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 23:05:07 -0400 From: Jud McCranie <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: 26 exponents At 09:44 PM 5/14/2001 -0400, Nathan Russell wrote: >However, that is still drawing a distinction between new and >experienced users. Well, so what if it does? It is an extremely minor difference. New users would still get first time LL tests - it just means that they wouldn't get exponents that someone else abandoned. It is an exponent thing, not a user thing. Many organizations have distinctions for new members. Non-voting members, provisional members, Fraternity pledges, etc. To a new user, what does it matter if he gets a brand new exponent instead of one that someone else abandoned in the same range? Why would a new user prefer an exponent someone else abandoned over one that no one else has been assigned? To me, it seems that (if anything) he would prefer a new one because there is a possibility of the person who abandoned it getting back to work on it and finishing it in the mean time. > For that matter, if a milestone is delayed by a >month or two, it doesn't significantly hurt everyone's overall odds of >finding a prime. I know, but it would be nice to know whether what seems to be M38 is or isn't M38. I can empathize with you here. However, I was a new user only a >little over a year ago, and if someone had said on the mailing list at >that time that new users should be given assignments chosen so that >they couldn't harm milestones, I would have been upset. They would still be contributing towards milestones. If there are exponents below a milestone that never have been assigned, they would get them. >Yes, it would be nice to say that we know for sure which Mersenne >prime is the thirty-eighth, but doing so does not speed us towards >discovering the thirty-ninth. But there could be one smaller than what now seems to be #38, because there are exponents in that range that haven't had even 1 LL. >For that matter, I am sure that there are users who have run a single >exponent and then left, Well, that's OK. Their work helps. Does anyone have an idea of the % of people who start and then quit w/o finishing an assignment? +------------------------------------+ | Jud McCranie | | | | former temporary part-time adjunct | | instructor of a minor university | +------------------------------------+ _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 23:32:08 -0400 From: Jud McCranie <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: 26 exponents At 09:44 PM 5/14/2001 -0400, Nathan Russell wrote: >However, that is still drawing a distinction between new and >experienced users. Well, how about this - new users can get an exponent that has been abandoned several times, but they must check in at least once a month to report the percentage done and expected completion date to show that they are making reasonable progress. It could even be automatic. Or maybe check in at 1 month, 2 months after that, and then every three months? Or is that too elitist too? +------------------------------------+ | Jud McCranie | | | | former temporary part-time adjunct | | instructor of a minor university | +------------------------------------+ _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 23:03:12 -0700 From: "Aaron Blosser" <[EMAIL PROTECTED]> Subject: Mersenne: Differences betwixt NTPrime and Prime95 > >Hmm... well, then again, I'm looking at the NTPrime. I've only got one > >machine running Prime95, and it's been so long... > > > >I thought it had all the same options though, but I could just be terribly > >mistaken. > > > >Running NTSetup (part of the NT service package), I show version 20.6.5... > I have version 20.6.1 - and the web page reads that all versions were > last updated June 15 2000. Something odd is going on... Turns out that Prime95 is indeed 20.6.1 and NTPrime shows up as 20.6.5. And yes, NTSetup will show the option I mentioned above, but Prime95 only has a checkmark for receiving occassional newsletters. How interesting. Well, clears up that mystery. Aaron _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com _________________________________________________________________________ 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 #851 ******************************
