20040525, 08:46  #1 
May 2003
27_{16} Posts 
28.0M  28.01M to 65 bits for starters
Hi,
I've started factoring the range to 65 bits. I'll probably go deeper as soon as the round is complete and I'll keep you posted. 
20040708, 12:33  #2 
May 2003
27_{16} Posts 
Now going at M28005269, only one exponent with a factor found so far

20040708, 14:20  #3 
May 2003
F8_{16} Posts 
One exponent? That's great! One less exponent for LL testing. Your couple hours of factoring just saved the project about a month of LL. Great job.

20040708, 17:15  #4 
May 2003
100111_{2} Posts 
Well, I would have expected a couple but then again, aren't the factors more rare when you TF the exponents 'deeper' ?

20040708, 21:42  #5 
6809 > 6502
"""""""""""""""""""
Aug 2003
101×103 Posts
2510_{16} Posts 
Consider that by factoring up to 55bits, many many factors have been removed (maybe 50% of all exponents are eliminated by factoring to 55bit). What you are doing is squeezing a few more out before P1 will get ~1% of the remaning. All of this proves that it is not prime and saves much time in the hunt.

20040709, 04:31  #6 
"Mark"
Feb 2003
Sydney
3×191 Posts 
All factors are good  they save on LL tests! One factor is well within what's expected: if I'm close in reckoning that you had TF'd 114 exponents from 2^64 to 2^65, you had 30% chance of one factor and 27% chance of two factors.
According to prime95's help file, the chance of finding a factor for an exponent between 2^b & 2^(b+1) is approximately 1/b. The killer is that the time taken doubles. It is very much worth it though  TF will still be costeffective up to 2^67 for these exponents. 
20040709, 05:29  #7 
May 2003
3·13 Posts 
Thanks for the explanations, guys.
I've been thinking about starting TF'ing the remaining exponents to 2^66 as soon as 2^65 is finished but I'm not sure how far I would get before the range will be in PrimeNet. Since I do some real work on the computer (a P42.76GHz), it's very hard to estimate the time needed. At the moment the time per exponent is a bit over three hours if I'm not doing anything special. If I shut down all the other processes the time might go down to two and a half hours so it would take about 57 hours per exponent when TF'ing to 2^66. Guess I'll just go with the range as long as I can EDIT: By the way, is it that TF'ing to 2^64 is not as effective on a SSE2capable machine as to 2^65? Last fiddled with by Boulder on 20040709 at 05:37 
20040709, 07:34  #8 
"Mark"
Feb 2003
Sydney
1000111101_{2} Posts 
Above 2^64, SSE2 gives a big advantage  I don't know by how much.
Below 2^62, Athlons outpace P4s apparently because of some fancy coding that does twoforone somehow. I don't know any more about why it is (and even this might be wrong!) or where nonSSE2 intel cpus fit in, but I do know that for TF below 2^62 an Athlon XP at 1533MHz is way faster than a P4 at 1800MHz. In between... not sure. 
20040709, 10:40  #9 
Aug 2002
Termonfeckin, IE
3^{2}×307 Posts 
These were some tests I ran a while back:
Time taken to complete 14366959 to 0.98% Code:
To Bit On PII 450 On P4 2533 Improv On 1333TB Improv 59 6 2.5 2.4 1.85 3.25 60 12 5 2.4 3.7 3.25 61 24 10 2.4 7.4 3.25 62 48 20 2.4 14.8 3.25 63 170 37.5 4.5 51 3.33 64 340 75 4.5 102 3.33 65 1540 180 8.5 480 3.21 Last fiddled with by garo on 20040709 at 10:41 
20041106, 11:18  #10 
May 2003
3×13 Posts 
Hi all,
I had an HD crash two months ago and lost a lot of work. I'm now attempting to factor the range to 2^65 before it hits the network, but can't promise anything. I remember seeing at least one number being factored so there's some motivation at least. Please notify me if the range goes out, I might not remember to log in often. 
20041118, 15:27  #11 
May 2003
3×13 Posts 
OK, I'll release the range as it should soon enter PrimeNet. I emailed the results to George, I nailed that one candidate which I remembered getting factored

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