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Forum: Programming 2013-05-31, 19:03
Replies: 104
Views: 7,560
Posted By J.F.
Oh hi, Jan (Feitsma) here. It seems this thread...

Oh hi, Jan (Feitsma) here. It seems this thread was temporary hi-jacked, sorry Paulunderwood... maybe any further such discussions should be moved to Charles' thread called 'Pseudoprimes'?

Yes a...
Forum: Lounge 2013-05-23, 07:16
Replies: 69
Views: 4,043
Posted By J.F.
I proudly installed the beasts onto my work...

I proudly installed the beasts onto my work monitor and they have started nibbling.
My colleagues seem to be in awe of this new display of nerdness. Or they avoid me even more now, I'm not sure yet....
Forum: Factoring 2013-03-04, 15:27
Replies: 125
Views: 10,269
Posted By J.F.
I would really like to get back into this...

I would really like to get back into this business. Years ago, I had much fun abusing University spare cycles to do some considerable sieving with you guys. I miss those times, I miss my cluster...
Forum: Computer Science & Computational Number Theory 2013-03-01, 15:00
Replies: 36
Views: 5,289
Posted By J.F.
It has been far too long since Galway and I...

It has been far too long since Galway and I 'published' the 2^64 (S)PSP results [1,2] without proof.
I feel embarrassed when I see people using the list, while running the risk that it is not...
Forum: PrimeNet 2013-02-24, 12:55
Replies: 2
Views: 587
Posted By J.F.
I am the Feitsma guy. Funny how a bit of...

I am the Feitsma guy. Funny how a bit of self-googling can bring you somewhere :).

When I was doing the base2-psp search, the main work involved a lot of trial-factoring on small mersenne...
Forum: Programming 2013-02-22, 14:06
Replies: 9
Views: 1,534
Posted By J.F.
I would call it "loss of precision" rather than...

I would call it "loss of precision" rather than overflow.
Doubles typically have 64 bits. So once the number becomes large enough (~2^64), lower digits become rubbish because there are not enough...
Forum: News 2013-02-05, 20:35
Replies: 571
Views: 58,078
Posted By J.F.
I get the impression the wait was worth it - news...

I get the impression the wait was worth it - news is catching on nicely!

Here at least, it is. In The Netherlands it is covered on a very popular news site www.nu.nl (http://www.nu.nl), but in...
Forum: News 2013-02-01, 15:43
Replies: 571
Views: 58,078
Posted By J.F.
Ahh, that's surprising and rather...

Ahh, that's surprising and rather disappointing... well you seem to have a good reason to do so.
Forum: News 2013-02-01, 10:40
Replies: 571
Views: 58,078
Posted By J.F.
please release the news!

I keep checking GIMPS to see a formal announcement. I hope it is released within the next few hours, otherwise the message might not be picked up properly by the media and it gets lost in the weekend...
Forum: Puzzles 2012-06-03, 20:30
Replies: 29
Views: 5,009
Posted By J.F.
Believe it or not, I made the #1 spot years ago...

Believe it or not, I made the #1 spot years ago on (back then) mathschallenge.net. Then, there were only ~110 problems and I could handle the competition at a particular problem, probably because...
Forum: Math 2010-08-11, 21:09
Replies: 44
Views: 4,119
Posted By J.F.
Charles asked me for the database of (base 2...

Charles asked me for the database of (base 2 Fermat) pseudoprimes I've been working on.
We've been sitting on this one for more than a half year, simply because I got sidetracked/lost focus. I am...
Forum: Factoring 2010-01-12, 20:07
Replies: 121
Views: 9,357
Posted By J.F.
Great job all! Raman, are you perhaps...

Great job all!

Raman, are you perhaps posting in the wrong thread?

Keep 'm coming, Fivemack. I'd slightly prefer 2- candidates, but you're the boss :).
Forum: Factoring 2009-11-23, 08:45
Replies: 21
Views: 1,185
Posted By J.F.
This applies to me also. But I'm ramping down...

This applies to me also. But I'm ramping down anyway due to other hobby-related activities, so feel free to ignore me in the decision making process.
Forum: Math 2009-11-22, 22:47
Replies: 6
Views: 544
Posted By J.F.
How do you figure that this is wrong? (-1,-1,-1)...

How do you figure that this is wrong? (-1,-1,-1) corresponds to (1,2,6) mod (2,3,7).
Forum: Lounge 2009-10-23, 16:27
Replies: 2
Views: 488
Posted By J.F.
A few years ago, I solved all puzzles at that...

A few years ago, I solved all puzzles at that moment, which were about 110. Then I stopped doing them for no particular reason.

I'd recommend those puzzles to anyone who wants to get started with...
Forum: Factoring 2009-10-13, 15:51
Replies: 121
Views: 9,357
Posted By J.F.
Thanks to Fivemack, I now have a fresh working...

Thanks to Fivemack, I now have a fresh working 16e executable :). Reserving 74-75M A+R, just to get things up and running.
Forum: Factoring 2009-09-16, 16:44
Replies: 121
Views: 9,357
Posted By J.F.
Unfortunately, 64-bit mode does not work for me: ...

Unfortunately, 64-bit mode does not work for me:


FATAL: kernel too old
Segmentation fault
while uname -a says

Linux hpcibm1 2.6.8-11-amd64-k8-smp #1 SMP Sun Oct 2 20:03:22 UTC 2005 x86_64...
Forum: Factoring 2009-09-15, 20:28
Replies: 121
Views: 9,357
Posted By J.F.
I'm having trouble finding a 16e binary... Would...

I'm having trouble finding a 16e binary... Would someone help me out?
Forum: Factoring 2009-07-21, 15:49
Replies: 50
Views: 4,202
Posted By J.F.
I have a very good use for factors of Mersenne's:...

I have a very good use for factors of Mersenne's: they can be used to generate base-2 pseudoprimes.
Forum: Lounge 2009-06-19, 06:51
Replies: 14
Views: 1,540
Posted By J.F.
beginner 5sec intermediate about 34, iirc ...

beginner 5sec
intermediate about 34, iirc
expert 98

I estimate this was about 5 years ago. Then I wrote an automatic solver in Pascal, so I would never have to play again ;).
Forum: Computer Science & Computational Number Theory 2009-06-04, 14:23
Replies: 36
Views: 5,289
Posted By J.F.
Well, we are not ready to release the used source...

Well, we are not ready to release the used source code in public. If we made it available now, it would be difficult to use as some sub-programs require quite large datafiles (8GB and some); plus...
Forum: Computer Science & Computational Number Theory 2009-06-02, 21:47
Replies: 36
Views: 5,289
Posted By J.F.
That's a bit premature, I think. Better to do so...

That's a bit premature, I think. Better to do so while referring to a website with details about the actual computation, or a paper. So I'll keep this in mind.

Btw, that sequence currently does...
Forum: Computer Science & Computational Number Theory 2009-06-02, 19:00
Replies: 36
Views: 5,289
Posted By J.F.
Time for an update. I have teamed up with...

Time for an update.

I have teamed up with Will Galway, we are still working on completing the 64-bit search. In response to a request of Ernst: the 10^17 search is now complete!
I've placed a...
Forum: Factoring 2009-05-06, 20:37
Replies: 45
Views: 3,286
Posted By J.F.
60-70M done

I ran into the badsched bug...
Note the drop in yield for 67.5M to 68M:


A00670a: total yield: 72908, q=67050043 (0.70423 sec/rel)
A00670b: total yield: 74765, q=67100009 (0.62354 sec/rel)...
Forum: Factoring 2009-05-01, 18:57
Replies: 45
Views: 3,286
Posted By J.F.
Reserving 60-70M.

Reserving 60-70M.
Showing results 1 to 25 of 72

 
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