Mersenne Digest Saturday, April 3 1999 Volume 01 : Number 540
----------------------------------------------------------------------
Date: Thu, 1 Apr 1999 18:08:50 -0800
From: "Robert Clark" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: RE: IMPORTANT: BUG IN VERSION 17 PRIME95
I am sure you must feel terrible, George. So although it may not
completely make you feel better, I just want you to know how much I
appreciate the incredible effort you have and are continuing to make on
this project. You have accomplished a great deal, and the whole
project has been handled in a completely professional manner.
There are thousands of us now searching for Mersenne primes who would
otherwise not have had the chance, and I imagine virtually all of us
are greatful to you for that.
Most of my machines are already converted. Let's find more!
Best regards,
Robert Clark
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Date: Thu, 1 Apr 1999 21:20:01 -0500
From: Bryan Fullerton <[EMAIL PROTECTED]>
Subject: Re: Mersenne: IMPORTANT: BUG IN VERSION PRIME95 17
On Thu, Apr 01, 1999 at 06:04:50PM -0500, George Woltman <[EMAIL PROTECTED]> wrote:
>
> After upgrading, you will get error messages that look like this:
> Error reading intermediate file: p6180331
> Renaming intermediate file q6180331 to p6180331.
> Error reading intermediate file: p6180331
> This is normal. Prime95 must discard the incorrect version 17
> save files.
Will it also discard version 17 save files for double checks? I'd assume so,
but thought I'd ask just to make sure.
Bryan
- --
Bryan Fullerton http://www.samurai.com/
Owner, Lead Consultant http://www.feh.net/
Samurai Consulting http://www.icomm.ca/
"No, we don't do seppuku." Can you feel the Ohmu call?
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Date: Thu, 1 Apr 1999 19:25:00 -0700
From: "Aaron Blosser" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: RE: IMPORTANT: BUG IN VERSION 17 PRIME95
> Alas, it is not an April Fools joke.
>
> Sorry again,
> George
Don't sweat it George.
So, just to clarify, if there were any results of exponents under ~4.2M,
they should be okay, meaning if I used 17.2 to doublecheck numbers in the 2M
range, they're fine? It's only all those ones higher done with 17.x that
need to be done again? And was it 17.1 *and* 17.2, or just 17.2?
These things happen. Better to find out now than another couple months down
the road.
I did notice that after upgrading on my machines, even those that were
double-checking exponents in the 2M range started over. Is that just to be
safe? Should we consider triple-checking all those that were double-checked
with 17.x?
At least trial-factoring wasn't affected! :-)
Will Scott be able to simply root out all tested numbers done with 17.x from
his database, or will they only start to show up as double-check tests in a
few months? Personally, I set my machines to double-check in the
meanwhile...until this is all sorted out.
Aaron
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Date: Thu, 1 Apr 1999 19:16:32 -0800
From: "Scott Kurowski" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: IMPORTANT: BUG IN VERSION PRIME95 17
> I've asked Scott to change Primenet to assign double-checking
> work to version 17 clients in the future.
PrimeNet's assignment rule was put into place shortly after George's
message. v17 clients asking for LL tests will get double-checking.
Folks, we now have more continuous CPU time on LL tests than ever
before in all of human history. And recently new members are joining
six times faster than usual, over 120 per day. GIMPS will bounce back
quickly.
Best regards,
scott
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Date: Thu, 01 Apr 1999 22:23:51 -0500
From: George Woltman <[EMAIL PROTECTED]>
Subject: Mersenne: Re: More on v17 bug
Hi once again,
At 09:59 PM 4/1/99 -0500, Bryan Fullerton wrote:
>I just downloaded the new mprime.tar.gz from the entropia.com FTP site,
>and it appears to still be v17.1.2 - the binaries are dated Nov 3, 1998.
Oops. It's been a long day. I'm uploading the proper ones now.
Bryan wrote earlier about deleting of v17 save files when you are
double-checking and uprgade to v18. The answer is yes you will
lose your good v17 work. If you are double-checking, please wait to
upgrade. I'll release version 18.1 that will toss the old
save file only if you are testing an exponent above 4.19 million.
Scott just contacted me. To have the server redirect all v17 clients
to double-checking work, I'll need to tweak v18 a little more so that
the server can distinguish between the two clients. Thus, unless we think
of something clever a version 18.1 will be released tomorrow. Version 18.0
will work properly, but will only get double-check assignments in the
future. Looks like I panicked and rushed 18.0 out a little hastily :)
>Aaron Blosser wrote:
>So, just to clarify, if there were any results of exponents under ~4.2M,
>they should be okay, meaning if I used 17.2 to doublecheck numbers in the 2M
>range, they're fine? It's only all those ones higher done with 17.x that
>need to be done again? And was it 17.1 *and* 17.2, or just 17.2?
Yes, all 17.x results above ~4.2M are affected. Your double-checks
in the 2M area are just fine.
>I did notice that after upgrading on my machines, even those that were
>double-checking exponents in the 2M range started over. Is that just to be
>safe? Should we consider triple-checking all those that were double-checked
>with 17.x?
I'll fix the program as noted above to not delete double-checking save files.
There is no need to triple-check.
>Will Scott be able to simply root out all tested numbers done with 17.x
Scott and I will work it out and get the numbers scheduled for a retest.
Best regards,
George
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Date: Thu, 01 Apr 1999 19:52:26 -0800
From: Spike Jones <[EMAIL PROTECTED]>
Subject: Re: Mersenne: IMPORTANT: BUG IN VERSION PRIME95 17
George, if it is a joke, you got me. {8^D If not, we forgive you.
You are still the man. We wont take your picture down off the
piano. {8^D spike
> > Please forgive me. I'm terribly sorry. I've discovered a bug
> > in version 17 of prime95 and its variants (ntprime, mprime, OS/2 version).
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Date: Thu, 01 Apr 1999 23:13:18 -0500
From: George Woltman <[EMAIL PROTECTED]>
Subject: Mersenne: Version 18.1
My last message of the day:
As alluded to earlier, version 18.1 is available. Those that
already upgraded to 18.0 can upgrade at your leisure.
Version 18.1 will get LL tests assigned to it, whereas version 18.0
will only get double-checks assigned.
The deleting of v17 save files below 4.2M is fixed.
Hopefully, I haven't added any new bugs in my haste.
Thanks for all the kind words and for your patience today.
It's bedtime,
George
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Date: Thu, 01 Apr 1999 23:23:06 -0500
From: [EMAIL PROTECTED]
Subject: Mersenne: Version 18, and non-text posts
First of all, the digest came on April 1 and was the first I heard of
either version 18 or the EFF prizes. Needless to say, it definately
smelled like a prank. It also started me thinking.
Originally, I read the source and kept a close eye on mprime. More
recently, though, I typically just download new versions and install
them without worrying. That being the case, I'd be alot happier if
the archives, and any announcements about either the client or server
came with signatures.
I'd also like to thank the people who corrected the html postings and
add one thing. Please avoid mime attachments altogether. For many
people on the digest they're a source of aggravation.
- -Matt
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Date: Thu, 1 Apr 1999 23:47:40 -0500 (EST)
From: "Vincent J. Mooney Jr." <[EMAIL PROTECTED]>
Subject: Mersenne: Win 3.11
I am still using Win 3.11 so I am not using Prime 95.
Is there an error in my software too? The executable is prime.exe
The range is in the 5,000,000 size.
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Date: Thu, 1 Apr 1999 21:30:40 -0800 (PST)
From: [EMAIL PROTECTED]
Subject: Mersenne: Factoring
Do I need to upgrade if I am only factoring?
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Date: Fri, 2 Apr 1999 00:43:01 EST
From: [EMAIL PROTECTED]
Subject: Mersenne: Aieee!
<<Please forgive me. I'm terribly sorry. I've discovered a bug
in version 17 of prime95 and its variants (ntprime, mprime, OS/2 version).
All Lucas-Lehmer tests above 4,194,304 (except those that were done as
a continuation of a v16 run) are no good. I feel sick.>>
Can you give us details on this bug and exactly why it starts affecting
exponents above that 4-mil number? (Augh - this means I've only tested one
number correctly). I'm very curious.
<<My records indicate that 10,794 of the 59,169 Lucas-Lehmer tests
above 4,194,304 will have to be discarded.>>
Why not all of them? Does the exponent have to be congruent to something or
other mod something else for the test to fail? Ahhhh - I'm even more curious
now. Is there a way that you can tell "Yup, this one's good." and "Nope,
ditch this one." Or is it a probabilistic thing and we have to doublecheck
all of them?
*groan*
S.T.L.
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Date: Fri, 2 Apr 1999 14:51:04 +0200 (CEST)
From: Henrik Olsen <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Version 18.1
On Thu, 1 Apr 1999, George Woltman wrote:
> As alluded to earlier, version 18.1 is available. Those that
> already upgraded to 18.0 can upgrade at your leisure.
> Version 18.1 will get LL tests assigned to it, whereas version 18.0
> will only get double-checks assigned.
> The deleting of v17 save files below 4.2M is fixed.
I hope you didn't do as said in the whatsnew.txt, shouldn't it be
KEEPING those below 4194304?
2) Only v17 save files below 4194304 are deleted.
- --
Henrik Olsen, Dawn Solutions I/S
URL=http://www.iaeste.dk/~henrik/
Get the rest there.
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Date: Fri, 2 Apr 1999 14:43:30 +0200
From: "Hoogendoorn, Sander" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: IMPORTANT: BUG IN VERSION PRIME95 17
Hi,
I'm at 92% off my current exponent, should i upgrade now or waste 2 more
days to produce a (possible wrong) result?
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Date: Fri, 2 Apr 1999 18:08:42 +0200 (CEST)
From: Henrik Olsen <[EMAIL PROTECTED]>
Subject: Re: Mersenne: A dreadful Virus called Milessa!
On Wed, 31 Mar 1999 [EMAIL PROTECTED] wrote:
> Gosh!
> I just read an artical about new virus called "Melissa". When a user
> opens this email in his or her MS Outlook, the MS Visual Basic macro
> virus automatically sends a copy of itself to the first 50 people in the
> user's address book. The subject heading reads, "Very important message
> from [user]", (user = the last person who unknowingly sent it.) It
> spreads like fire, from anyone who was unintentionally sent this email,
> opening this email will breed another 50 copies. I read it in England's
> Telegraph newspaper (31 March, 1999). Summery: dont open any messages
> with the "important message..." business in the heading. I just thought a
> bunch of emailers like you guys might need this info. Let me know if you
> find out anything about this virus.
>
> -oliver
This is a report that would normally have triggered all my hoax detectors
due to the total lack of references, but luckily I'd already been informed
by a more reliable source.
For more info and the straight dope, check
http://www.cert.org/advisories/CA-99-04-Melissa-Macro-Virus.html
- --
Henrik Olsen, Dawn Solutions I/S
URL=http://www.iaeste.dk/~henrik/
Get the rest there.
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Date: Fri, 2 Apr 1999 18:45:22 +0200 (CEST)
From: Henrik Olsen <[EMAIL PROTECTED]>
Subject: Re: Mersenne: IMPORTANT: BUG IN VERSION PRIME95 17
On Thu, 1 Apr 1999, George Woltman wrote:
> As alluded to earlier, version 18.1 is available. Those that
> already upgraded to 18.0 can upgrade at your leisure.
> Version 18.1 will get LL tests assigned to it, whereas version
> 18.0 will only get double-checks assigned.
> The deleting of v17 save files below 4.2M is fixed.
Somehow I find it suspicious that the assignments status report
http://entropia.com/primenet/status.txt
shows no change at all in the pattern of assignments, something that
should have been immediately visible if ~10000 exponents had been recycled
for first time LL-testing and if all old clients should only be getting
double checking assignments.
In the last three days, about the same number of exponents have been
assigned in the 7.3M range each day, with no indication of the drop that
would have been expected if all 17.* clients only got DoubleChecking
assignments.
Ditto for then expected jump in doublechecking assignments.
Conclusion:
Either it really IS an Aprils fool joke, or Scott haven't updated the
primenet software, something that doesn't ring true with his previous
performance.
Henrik
- --
Henrik Olsen, Dawn Solutions I/S
URL=http://www.iaeste.dk/~henrik/
Get the rest there.
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Date: Fri, 2 Apr 1999 21:17:41 +0200
From: "Jean-Yves Canart" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: IMPORTANT: BUG IN VERSION PRIME95 17
George,
I have plenty of reasons to feel that you should not be so worried with what
happened :
- - Since I joined GIMPS project more than three years ago, you always
impressed me with your thorough work.
You have proved several times your professionalism, up to the way you
announced this bad news, honestly and humbly.
- - Don't forget your motto : 'just for fun'. A small bug in a program whose
primary goal is to entertain all of us is nothing compared with e.g what
happens now in Kosovo..
- - Even the great Mersenne himself commited two bugs, by incorrectly
'proving' primality of M(67) and M(257).
You have been wrong only once...
George, the hardest is now behind us, let's discover M38 quickly and
everything will be forgotten.
Regards,
Jean-Yves
- -----Original Message-----
From: George Woltman <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Date: 02 April 1999 01:07
Subject: Mersenne: IMPORTANT: BUG IN VERSION PRIME95 17
>Hi all,
>
> Please forgive me. I'm terribly sorry. I've discovered a bug
>in version 17 of prime95 and its variants (ntprime, mprime, OS/2 version).
>All Lucas-Lehmer tests above 4,194,304 (except those that were done as
>a continuation of a v16 run) are no good. I feel sick.
>
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Date: Fri, 02 Apr 1999 14:12:09 -0500
From: George Woltman <[EMAIL PROTECTED]>
Subject: Mersenne: Questions answered on v17 bug
Hello,
At 09:30 PM 4/1/99 -0800, [EMAIL PROTECTED] wrote:
>Do I need to upgrade if I am only factoring?
No. The bug does not affect factoring or double-checking below 4,194,304.
At 11:47 PM 4/1/99 -0500, Vincent J. Mooney Jr. wrote:
>I am still using Win 3.11 so I am not using Prime 95.
>Is there an error in my software too? The executable is prime.exe
>The range is in the 5,000,000 size.
If you are using version 17 of prime.exe then you are affected.
At 02:51 PM 4/2/99 +0200, Henrik Olsen wrote:
>I hope you didn't do as said in the whatsnew.txt, shouldn't it be
>KEEPING those below 4194304?
>2) Only v17 save files below 4194304 are deleted.
You are correct. I will update the whatsnew.txt file today.
At 02:43 PM 4/2/99 +0200, Hoogendoorn, Sander wrote:
>I'm at 92% off my current exponent, should i upgrade now or waste 2 more
>days to produce a (possible wrong) result?
Upgrade now. Your 92% of work is no good (unless you started testing
the exponent with version 16 - if so, version 18 will not delete your
save file).
At 12:28 PM 4/2/99 +0200, Philip Heede wrote:
>- The Linux MPrime version correctly reports itself as v18.1.2 when run
>as "./mprime -v". But the 'menu-item' Help/About in the configuration
>menu still reports v17.1.2
I will fix this today.
At 12:43 AM 4/2/99 EST, [EMAIL PROTECTED] wrote:
>Can you give us details on this bug and exactly why it starts affecting
>exponents above that 4-mil number?
The bug was in the routine mulmod which was supposed to compute a * b mod c
The implementation was a rather sloppy:
unsigned long tmp;
tmp = a * (b & 0x3FF);
tmp += ((a << 10) % c) * (b >> 10);
return (tmp % c);
You can see in the first computation of tmp there will be an overflow if
a exceeds 2^22 or 4194304. The new implementation is:
double tmp;
unsigned long q;
tmp = (double) a * (double) b;
q = (unsigned long) (tmp / (double) c);
return ((unsigned long) (tmp - (double) q * (double) c));
This implementation isn't perfect, but will work as long as a * b does
not exceed 53 bits.
The old mulmod code was adequate in version 16, but in version 17 I started
calling it with the "a" value being the shifted bit number (i.e. where to
subtract the two from in each Lucas-Lehmer iteration).
><<My records indicate that 10,794 of the 59,169 Lucas-Lehmer tests
>above 4,194,304 will have to be discarded.>>
>
>Why not all of them?
All version 16 results are OK. They look like this:
M6521737 is not prime. Res64: 12340D1080151234. WS1: D4D7319A
If the test started in version 16 and was completed by version 17,
the result is OK (the shifted bit value was always zero). They look
like this:
M4317283 is not prime. Res64: 1234FB37253F1234. WT1: E9B7F252,0,80000000
Results computed entirely by v17 are no good. They look like this:
M6632413 is not prime. Res64: 123484E907DD1234. WT1:
AC762921,1322056,00000000
Best regards,
George
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Date: Fri, 02 Apr 1999 14:23:53 -0500
From: George Woltman <[EMAIL PROTECTED]>
Subject: Mersenne: Re: Is bug a hoax?
Hi all,
At 06:45 PM 4/2/99 +0200, Henrik Olsen wrote:
>Somehow I find it suspicious that the assignments status report
>http://entropia.com/primenet/status.txt
>shows no change at all in the pattern of assignments, something that
>should have been immediately visible if ~10000 exponents had been recycled
>for first time LL-testing
The first task was to fix the program. Scott and I are now working out
a plan to get the 10000 affected exponents back in the queue. That
should happen sometime over the next few days.
There should be a slight uptick in double-check assignments that go out.
Unfortunately, the server cannot contact the v17 clients and tell them to
ditch their current assignments and get new ones. So only those that
are running low on work will get double-check assignments.
Best regards,
George
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Date: Fri, 02 Apr 1999 22:24:07 +0200
From: Henk Stokhorst <[EMAIL PROTECTED]>
Subject: Mersenne: Bug in 17.x and the $50,000
L.S.,
I hope that one of those numbers that need to be redone does not turn into a cash
winner. It would make the person who did the first attempt feel a little too silly.
If I win $50,000 and it was previously assigned I will share part of it, $5,000
(10%) to the misfortunate returner of a wrong residu.
YotN,
Henk Stokhorst.
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Date: Fri, 2 Apr 1999 14:02:04 -0700
From: "Aaron Blosser" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: Re: Is bug a hoax?
> The first task was to fix the program. Scott and I are now working out
> a plan to get the 10000 affected exponents back in the queue. That
> should happen sometime over the next few days.
>
> There should be a slight uptick in double-check assignments that go out.
> Unfortunately, the server cannot contact the v17 clients and tell them to
> ditch their current assignments and get new ones. So only those that
> are running low on work will get double-check assignments.
Would I be right in assuming that Primenet keeps track of which version was
used to check in a certain result?
If so, what about folks that manually check in numbers? Does one of those
numbers besides the residue indicate version?
And once all suspect results are identified, those exponents will be removed
so they can be retrieved as LL tests rather than double-checks...yes?
Otherwise, double-checking will take a while to get up to those numbers
since the current range of double-checks being passed out are in the 2^2.6M
range...
And finally, is there a plan to send an email notice to everyone? We on
this list found out, but alot of folks are probably running the software but
aren't on the list...I know I was for quite some time. They might like to
know that their current test needs to be restarted right away.
I'm just full of questions... :-) Fortunately (?) they're turning off our
building power this weekend so I was going to have to work on all my
machines anyway...
Aaron
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Date: Fri, 02 Apr 1999 16:56:34 -0500
From: George Woltman <[EMAIL PROTECTED]>
Subject: Mersenne: RE: More v17 questions
Hi,
At 02:02 PM 4/2/99 -0700, Aaron Blosser wrote:
>Would I be right in assuming that Primenet keeps track of which version was
>used to check in a certain result?
Scott can answer this best. He may not be able to tell if a result
was finished by v17 and started by v16.
>If so, what about folks that manually check in numbers? Does one of those
>numbers besides the residue indicate version?
Yes, this was described in an earlier email. It's the WTx and the
second number after that being non-zero.
>And once all suspect results are identified, those exponents will be removed
>so they can be retrieved as LL tests rather than double-checks...yes?
Correct.
>And finally, is there a plan to send an email notice to everyone?
Yes. Mersenne Newsletter #15 will be emailed soon.
Best regards,
George
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Date: Fri, 02 Apr 1999 17:34:59 EST
From: "Foghorn Leghorn" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Questions answered on v17 bug
George Woltman wrote:
>The bug was in the routine mulmod which was supposed to compute a * b
mod c
>The implementation was a rather sloppy:
> unsigned long tmp;
> tmp = a * (b & 0x3FF);
> tmp += ((a << 10) % c) * (b >> 10);
> return (tmp % c);
>You can see in the first computation of tmp there will be an overflow
if
>a exceeds 2^22 or 4194304. The new implementation is:
> double tmp;
> unsigned long q;
> tmp = (double) a * (double) b;
> q = (unsigned long) (tmp / (double) c);
> return ((unsigned long) (tmp - (double) q * (double) c));
>This implementation isn't perfect, but will work as long as a * b does
>not exceed 53 bits.
This got me thinking, since I've had a use for modular multiplication in
some of the little programs that I've bee writing. Based on your code, I
wrote the following:
unsigned long mulmod(unsigned long a, unsigned long b, unsigned long n)
{
long double tmp, q;
tmp = a * (long double)b;
q = floorl(a * (long double)b / n);
return tmp - q * n;
}
In my testing, this appears to give the correct result for any 32-bit
values of a, b, and n, thanks to the 64-bit precision of Intel's 80-bit
floating point type. Is there anything wrong with this approach? It
depends on having a long double version of the floor function, which is
available on my Borland compiler.
Get Your Private, Free Email at http://www.hotmail.com
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Date: Fri, 2 Apr 1999 18:52:37 EST
From: [EMAIL PROTECTED]
Subject: Mersenne: Goodbye...
After the latest two events, I am saying good-bye to Prime95.
The latest rumors (?) caused some concern, but then I upgraded
to version 18.1 and lost two months of work (it deleted the
intermediate files). That did it. Ah, well, it has been fun for
two years. I'll probably miss the little red icon -- for a while.
Randy Given
[EMAIL PROTECTED]
http://members.aol.com/GivenRandy
public key at http://members.aol.com/GivenRandy/pgpkey.asc
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Date: Fri, 2 Apr 1999 20:36:24 -0500
From: "Chad Davis" <[EMAIL PROTECTED]>
Subject: Mersenne: Recent Happenings
Hi,
I'd just like to chime in with what I'm sure must be the feelings of
most of us here. We understand that accidents happen, bugs creep in,
especially ones that are subtle and hard to detect. Without George's
expertise and long hours spent programming and organizing the effort, very
very few of us would be searching for Mersennes. It continues to be a highly
enjoyable experience, so I want to take this opportunity to echo Robert,
Jean-Yves, and others in saying Thank You George.
Just For Fun,
Chad
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Date: Fri, 2 Apr 1999 19:08:43 -0700
From: "Aaron Blosser" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: Goodbye...
> From: [EMAIL PROTECTED]
> After the latest two events, I am saying good-bye to Prime95.
> The latest rumors (?) caused some concern, but then I upgraded
> to version 18.1 and lost two months of work (it deleted the
> intermediate files). That did it. Ah, well, it has been fun for
> two years. I'll probably miss the little red icon -- for a while.
>
> Randy Given
Hmmm...I'd ask you to reconsider. Remember, it's something to harness that
extra computing power that otherwise is wasted. Sure, it's a setback to
lose 2 months worth. Heck, I had NTPrime running on about 20 processors for
quite a while and now those exponents >4.2M need to be rechecked, but what
else would those computers do in their spare time?
Heck, I had a terrible setback in regards to prime numbers, my own fault of
course, but I still use what computers I'm *allowed* to use (heh) looking
for primes. Just today I scrounged up a 200MHz PPro PC from spare parts at
work and got it searching...it's fun in some strange way.
So, I hope you'll reconsider. If not, I understand that too.
Aaron
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Date: Fri, 2 Apr 1999 19:50:37 -0800
From: Greg Hewgill <[EMAIL PROTECTED]>
Subject: Mersenne: Version 17 errors
First, kudos to George for the professional way in which this version 17
problem has been handled. It's an unfortunate setback, but these things do
happen.
I checked most of my machines today, and most of the ones I could easily reach
were either running 16.x doing large exponents, or were running version 17 for
double checking. So far, only one running version 17 for large LL tests had to
be upgraded.
However, some of the machines I run are not as accessible, and I can't reach
them right away. It would be very helpful if there were a way to request,
from the Primenet server, a list of machines and the version reported by their
last result. This would make administration of more than a few machines much
easier. Any possibility of this?
Greg Hewgill
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Date: Fri, 02 Apr 1999 22:51:04 -0500
From: George Woltman <[EMAIL PROTECTED]>
Subject: Mersenne: Re: Enhanced Mulmod Code
Hi,
At 05:34 PM 4/2/99 EST, Foghorn Leghorn wrote:
>I wrote the following:
>
>unsigned long mulmod(unsigned long a, unsigned long b, unsigned long n)
>{
> long double tmp, q;
> tmp = a * (long double)b;
> q = floorl(a * (long double)b / n);
> return tmp - q * n;
>}
>
>In my testing, this appears to give the correct result for any 32-bit
>values of a, b, and n, thanks to the 64-bit precision of Intel's 80-bit
>floating point type. Is there anything wrong with this approach?
A compiler is allowed to store values in 53-bit precision memory locations
at any point during the floating point computation. Thus, whether or
not your code works on any 32-bit values is completely compiler-dependent.
Best regards,
George
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Date: Fri, 2 Apr 1999 22:02:37 -0800
From: "Scott Kurowski" <[EMAIL PROTECTED]>
Subject: Mersenne: RE: Version 17 errors
Hi Greg,
> It would be very helpful if there were a way to request,
> from the Primenet server, a list of machines and the
> version reported by their last result. This would make
> administration of more than a few machines much
> easier. Any possibility of this?
Sure. If there is enough demand I can put up a web page for this, but
short of that please email me.
Here are your v17 machines:
machine_id
- -------------
aup
bdc
fuzzybutt
gmab
greg-home-p2
horntoad
imcs
monica
qa
webs_r_us
And here are your v16 machines:
machine_id
- -------------
dan
demo
devnts2
greg
greg-home-px
ozzie
popmail
prime1
prime2
prime3
swg
winterm
Best regards,
scott
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Date: Sat, 3 Apr 1999 09:38:38 +0200
From: "Michiel van Loon" <[EMAIL PROTECTED]>
Subject: Mersenne: New version of PRIMEOS2
Hi all OS/2 users,
Since also PRIMEOS2 and PRIMEEMX have been affected by the bug I have
uploaded new versions of both programs to:
http://www.xs4all.nl/~mfvl/prime
These versions are (again) the ports of MPRIME V18.1.2 containing the mulmod
corrections as mentioned on this list before.
Everyone using the V17 port (Version 3.2.x) should upgrade.
With kind regards,
Michiel van Loon
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Date: Sat, 3 Apr 1999 07:44:57 -0000
From: [EMAIL PROTECTED]
Subject: Re: Mersenne: Goodbye...
A small suggestion. It's only a small point, and would only bother people who are
overwhelmingly worried by rankings, but...
Could we not credit those users who have had their intermediate files wiped as a
result of updating to v18 for the work carried out up to the last time they
checked in the exponent to PrimeNet?
e.g. if someone was working on an exponent around 5 million (256K FFT) and they
had checked in to PrimeNet that they were at exponent x with v17, but started the
run again with v18, they should be credited with 0.776*x P90 CPU seconds for the
"lost" work.
This could be seen as a sort of "good will" gesture to those who have lost work.
After all, if they let the exponent continue to the end & report it before
upgrading, they would get full credit, for a bad result.
Though, quite honestly, there are more urgent things to do, like knocking the
database back into shape. However, if the server logs contain suitable
information, I'm sure they could be scanned to retrieve the information neccessary
to implement my suggestion.
Scott, if there's any way you could send me a description of the log file format,
(and perhaps a small extract), I could look at writing a program which you could
use to do the processing, but I won't be able to look at it for a week or two.
Regards
Brian Beesley
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Date: Sat, 03 Apr 1999 09:42:05 -0600
From: kilfoyle <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Recent Happenings
yep yep yep George... the search continues. It is not deterred by a small
bug. Bugs are always lurking. I also thank George for his years of effort..
THANKS GEORGE!!!!!!
Michael
Chad Davis wrote:
> Hi,
> I'd just like to chime in with what I'm sure must be the feelings of
> most of us here. We understand that accidents happen, bugs creep in,
> especially ones that are subtle and hard to detect. Without George's
> expertise and long hours spent programming and organizing the effort, very
> very few of us would be searching for Mersennes. It continues to be a highly
> enjoyable experience, so I want to take this opportunity to echo Robert,
> Jean-Yves, and others in saying Thank You George.
>
> Just For Fun,
> Chad
>
> ________________________________________________________________
> Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm
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Date: Sat, 3 Apr 1999 09:39:08 -0800 (PST)
From: [EMAIL PROTECTED]
Subject: Re: Mersenne: Goodbye...
I have to disagree here. People will be studying this project many years
in the future. This little faux pas is part of the project and adds to the
total work required to do it (Did anyone REALLY think a project this BIG
would come off error free???). For historical purity reasons, I say leave
the work values as they are.
At work I am a developer for the worlds biggest computing software upgrade
(The Boeing DCAC/MRM program, "Over $2 Billion served"). Compared to this
project, DCAC/MRM is a freakin' circus. Keeping good configuration
management is the hardest thing to do (Even harder than raising kids???).
Guys like George Wotlman and Linus Torvalds should be given medals for
their magical ability to keep things under control while keeping things
productive.
Lets keep things accurate!
- -Chuck
On Sat, 3 Apr 1999 [EMAIL PROTECTED] wrote:
> A small suggestion. It's only a small point, and would only bother people who are
> overwhelmingly worried by rankings, but...
>
> Could we not credit those users who have had their intermediate files wiped as a
> result of updating to v18 for the work carried out up to the last time they
> checked in the exponent to PrimeNet?
>
> e.g. if someone was working on an exponent around 5 million (256K FFT) and they
> had checked in to PrimeNet that they were at exponent x with v17, but started the
> run again with v18, they should be credited with 0.776*x P90 CPU seconds for the
> "lost" work.
>
> This could be seen as a sort of "good will" gesture to those who have lost work.
> After all, if they let the exponent continue to the end & report it before
> upgrading, they would get full credit, for a bad result.
>
> Though, quite honestly, there are more urgent things to do, like knocking the
> database back into shape. However, if the server logs contain suitable
> information, I'm sure they could be scanned to retrieve the information neccessary
> to implement my suggestion.
>
> Scott, if there's any way you could send me a description of the log file format,
> (and perhaps a small extract), I could look at writing a program which you could
> use to do the processing, but I won't be able to look at it for a week or two.
>
> Regards
> Brian Beesley
> ________________________________________________________________
> Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm
>
--
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: WWW: http://www.silverlink.net/poke : Boycott Microsoft :
: E-Mail: [EMAIL PROTECTED] : http://www.vcnet.com/bms :
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Date: Sat, 03 Apr 1999 12:47:52 -0500
From: Jud McCranie <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Recent Happenings
At 09:42 AM 4/3/99 -0600, kilfoyle wrote:
>yep yep yep George... the search continues. It is not deterred by a small
>bug.
I'm not deterred either. In fact, I added a second machine since I found
out about the bug.
+-----------------------------------------------------------+
| Jud McCranie [EMAIL PROTECTED] |
| |
| "We should regard the digital computer system as an |
| instrument to assist the number theorist in investigating |
| the properties of his universe - the natural numbers." |
| -- D. H. Lehmer, 1974 (paraphrased) |
+-----------------------------------------------------------+
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End of Mersenne Digest V1 #540
******************************
