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Old 2015-11-21, 22:24   #1
dbaugh
 
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I had trial factored 12827821 from 2^64 through 2^78. ANONYMOUS had trial factored up to 2^64. No factors had been found.

2^78 to 2^79, 2^79 to 2^80 and 2^80 to 2^81 were being trial factored on three different machines. A factor was found and reported in the 2^80 to 2^81 range. PrimeNet will not allow the two lower ranges which are now completed to be reported as no-factor. If you look up the exponent it appears as though 2^78 to 2^79 and 2^79 to 2^80 have not been searched for factors. This is not true.

Even if there is no credit available for searching for additional factors of exponents for which a factor has been found, there should be a way to report that the ranges have been searched. What do I do now?

Last fiddled with by dbaugh on 2015-11-21 at 22:25 Reason: typo
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Old 2015-11-21, 23:44   #2
snme2pm1
 
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Quote:
Originally Posted by dbaugh View Post
2^78 to 2^79, 2^79 to 2^80 and 2^80 to 2^81 were being trial factored on three different machines. A factor was found and reported in the 2^80 to 2^81 range.
The hazard arose right there, especially if results were automatically submitted to PrimeNet.
Quote:
Originally Posted by dbaugh View Post
PrimeNet will not allow the two lower ranges which are now completed to be reported as no-factor. ... What do I do now?
You might petition George with the details of the work, though I don't know if there is a convenient mechanism to introduce such results.
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Old 2015-11-22, 02:35   #3
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It is safest to make sure that TF results get submitted in order. MISFIT can do this for you, if you run Windows. IIRC, people use it to coordinate multiple machines. I use it to run multiple GPUs in the same system.

In the Configuration Editor, there is an option to NOT export 'partial results.' The entire range assigned must be complete before MISFIT will submit it, and it will not send them out of order.

EDIT: Sorry for providing useless information, if you are not a Windows user.

Last fiddled with by kladner on 2015-11-22 at 02:39
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Old 2015-11-22, 03:41   #4
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Quote:
Originally Posted by snme2pm1 View Post
You might petition George with the details of the work
+1
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Old 2015-11-22, 10:14   #5
LaurV
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It smells like a p-1 result (B1=29k, B2=3M6 would find it in minutes). I won't give TF credit for lower bits. Sorry.
We already had too many guys here trying to get lots of TF credit for P-1 factors.
You may be a honest guy, but I won't believe you went to days/weeks of TF before trying minutes of P-1 - you were silly in this case, but if that is the case indeed, you should have some other work done and reported, and eventually factors found in this range, at these bitlevels. Have you?

Last fiddled with by LaurV on 2015-11-22 at 10:17
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Old 2015-11-22, 16:15   #6
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More ignorant than silly. I do not understand p-1 and how it can be used to clear a bit range of factors. My main interest is that there is a record that these bit ranges have been exhaustively searched and there are no factors there. Here is a small selection of some other exponents I have searched at these bit levels and beyond with no factors found: 9007753, 9007903, 9027433.

If p-1 is so quick, I asked a couple of years ago for a factor of 9007753. Please find one for me.
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Old 2015-11-22, 16:20   #7
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Another question first: how long did it take you to TF 9007753 to 82 bits?
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Old 2015-11-22, 16:30   #8
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I started at 68 to 69 four years ago, so I do not know the total time spent. It took just over two and a half months to do 81 to 82.
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Old 2015-11-22, 20:59   #9
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How does one calculate B1 and B2 from exponent and factor? I saw another post where you said a guys B2 was too big to be p-1. People were questioning his paucity of factors from TFing. It turned out his TF factors were being recorded as p-1. That was happening to me regularly a year ago but not this time.
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Old 2015-11-23, 02:49   #10
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Quote:
Originally Posted by dbaugh View Post
How does one calculate B1 and B2 from exponent and factor? I saw another post where you said a guys B2 was too big to be p-1. People were questioning his paucity of factors from TFing. It turned out his TF factors were being recorded as p-1. That was happening to me regularly a year ago but not this time.
This is a good and practical question, so lets answer it:

You have to factor q-1, where q is your found factor. As all the factors are of the form 2*k*p+1, then your q-1 is 2*k*p for some positive k. You take out p and 2 from the list of the factors, and what is left is your k.
The P-1 factoring algorithm would find that factor q if either (1) B1 is larger than the largest factor of k (or equal), or (2) if B1 is larger (or equal) than the second largest factor of k and B2 is larger than the largest (or equal, technically, B2 is larger than the largest minus something, depending of your memory amount).

Which one of the two, (1) or (2) would find the factor faster depends on the difference between the highest and second highest factors of k, and depends also of how much memory you give to P-1 program. More memory makes stage 2 of the algorithm faster (in practice, it will take the same time as stage 1, it just goes deeper, using a higher B2 and increasing your chances to find a factor, but that is different story).

Example for your factor (we use pari/gp to factor such small numbers):

Code:
gp > factorint(1426192839661371189084169-1)
time = 99 ms.
[       2 3]
[       3 1]
[      43 1]
[    1069 1]
[   28493 1]
[ 3536957 1]
[12827821 1]
gp >
So, your q-1 factors like 2[COLOR=Magenta]3[/COLOR]*3*43*1069*28493*3536957*12827821, from which we take out one 2 and the "p" (your exponent, marked purple) , and we get your k being k=2[COLOR=Magenta]2[/COLOR]*3*43*1069*28493*3536957

So, (1) Running P-1 with B1 higher than (or equal to) 3536957 would find the factor q in stage 1.
Or, (2) Running P-1 with B1>=28493 and B2>=3536957 would find your factor in stage 2.

For this particular case, the factor would be found faster with a B1~=30~40k, and a B2~=3M6, but those can vary according with your memory allocation. Generally, we use B2~=100*B1, because stage 2 is about 100 times faster than stage 1, and the best result is when the algorithm spends the same amount of time in each stage.

Anyhow, you should always run P-1 to some limits before attempting such Long-Time TF jobs. You just wasted a lot of your time and resources, when you could do other things.

For this particular case, P-1 would be a few minutes job, with a "right guess" of B1 and B2. But as the "right guess" we never do, and we just use generic B1 and B2, you could spent maximum a few hours for this factor.

OTOH, I still think you found this factor by P-1 or ECM. I see you are running a lot of TF and ECM in that range, so you are not exactly innocent there Therefore it seems to me you know what you are doing, and you usually stop at 75-76 bits, so my next question would be why you decided to go to 81-82 bits for this very particular exponent?

I may be totally wrong there, and you may be a honest guy, you know... but as I said, we have a lot of guys (and guls, hehe) here trying to take advantage of the system, and sooner or later we catch them. The system is not fool-proof, it is designed for people who want to contribute and do real, honest work. If you don't know, then you better ask. We will answer the questions if we know the answer, and someone will help you to use your resources better for you and the project. There is no shame to ask, we even appreciate it, we say, hey, look, a guy who wants to learn - those are rare...

Last fiddled with by LaurV on 2015-11-23 at 03:03 Reason: added some colors, fixed some grammar
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Old 2015-11-23, 05:07   #11
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Great tutorial! Of the 400+ LL's I have done, 9007753 was my one bad residue. I would like to redeem myself with this exponent by finding a factor of it. I do high TF-ing of small exponents because with my GPUs I can get a lot of credit fast. My original ID (DB11) from 1997 did not migrate and I lost 317 LLs. The first was 2194013. I am revisiting those exponents and ones near them with TF.

I have used ECM to do what you suggest I use P-1 for. That is, find factors so I do not need to TF.
e.g., 5551699, 5592527, 9027611, 11003933.

Here is a copy of the results file which includes the factor you seem to find of questionable provenance. It was finding that factor that inspired me to catch up on my submissions.

[Sun May 31 13:10:10 2015]
no factor for M11003939 from 2^78 to 2^79 [mfaktc 0.21 barrett87_mul32_gs]
[Thu Jun 18 06:01:49 2015]
no factor for M11003939 from 2^79 to 2^80 [mfaktc 0.21 barrett87_mul32_gs]
[Tue Jul 28 09:22:56 2015]
no factor for M9007903 from 2^80 to 2^81 [mfaktc 0.21 barrett87_mul32_gs]
[Sun Sep 06 13:29:03 2015]
no factor for M9027433 from 2^80 to 2^81 [mfaktc 0.21 barrett87_mul32_gs]
[Sun Oct 11 00:18:40 2015]
no factor for M11003939 from 2^80 to 2^81 [mfaktc 0.21 barrett87_mul32_gs]
[Mon Nov 09 13:27:31 2015]
M12827821 has a factor: 1426192839661371189084169 [TF:80:81:mfaktc 0.21 barrett87_mul32_gs]
[Mon Nov 09 17:09:41 2015]
found 1 factor for M12827821 from 2^80 to 2^81 [mfaktc 0.21 barrett87_mul32_gs]

Again, my real issue is that if you look at the exponent status of 12827821 it appears as though the range from 2^78 to 2^80 has not been searched. It has. If a bigger factor has been found it should still be possible to document cleared ranges even if no credit is given. If I had submitted the results in a different order everything would have been fine.
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