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-   -   How unlucky have I been? (https://www.mersenneforum.org/showthread.php?t=18038)

ixfd64 2013-03-29 03:44

How unlucky have I been?
 
I just realized I've completed 218 P-1 assignments without finding a factor. Yikes.

Anyone ever had a longer dry spell?

petrw1 2013-03-29 03:48

[QUOTE=ixfd64;335308]I just realized I've completed 218 P-1 assignments without finding a factor. Yikes.

Anyone ever had a longer dry spell?[/QUOTE]

About 3 times that many rounds of golf and not a single hole-in-one!

Uncwilly 2013-03-29 04:02

[QUOTE=ixfd64;335308]I just realized I've completed 218 P-1 assignments without finding a factor. Yikes.[/QUOTE]
Can I guess 48 of the numbers?:razz:

Mr. P-1 2013-03-29 09:14

[QUOTE=ixfd64;335308]I just realized I've completed 218 P-1 assignments without finding a factor. Yikes.

Anyone ever had a longer dry spell?[/QUOTE]

I don't recall how many, but some years ago, I went about 5 months without finding any. I think I was doing about one per day, so that wouldn't be as many as yours.

I recommend you try some torture testing. Perhaps your hardware is beginning to flake. Otherwise just carry on. Every P-1 you do is a P-1 that someone else won't have to do, and which, if they did, would have been done a lot less efficiently that you did it.

TimSorbet 2013-03-29 12:01

Assuming an average 3.5% chance of success per test (and assuming I'm calculating correctly), there was only a 1 in ~2400 probability that none of the 218 would result in a factor. You should've expected around 7.8 factors. Either you've been VERY unlucky, or your hardware is unstable.

petrw1 2013-03-29 14:17

126 is my worst
 
In my life I have done 2,925 P-1 (on several PC's).
My longest streak was 126 with no factors.
But I also had a streak of 3 in a row and 4 out of 5.
182 total factors found: 6.22%

ixfd64 2013-03-29 16:03

[QUOTE=Mini-Geek;335338]Assuming an average 3.5% chance of success per test (and assuming I'm calculating correctly), there was only a 1 in ~2400 probability that none of the 218 would result in a factor. You should've expected around 7.8 factors. Either you've been VERY unlucky,[B] or your hardware is unstable.[/B][/QUOTE]

I doubt the latter is the case, considering most of those results are from three different computers (I have four doing P-1 at the moment).

Xyzzy 2013-03-29 16:08

As a test, run an exponent that has a P-1 factor already found?

:mike:

petrw1 2013-03-29 17:45

[QUOTE=ixfd64;335364]I doubt the latter is the case, considering most of those results are from three different computers (I have four doing P-1 at the moment).[/QUOTE]

No offense; just checking:

Doing Stge 1 AND 2?
Enough RAM allocated to give you an estimate of at least 4% or more?

Your resul last 365 days are only about 2.7%. Seems low.
Could be one of the 2 reasons above OR just from your unlucky streak.

But then your lifetime is over 6%. That's good.

chalsall 2013-03-29 18:09

[QUOTE=Xyzzy;335367]As a test, run an exponent that has a P-1 factor already found?

:mike:[/QUOTE]

If you want to run some tests, here are ten which had a factor found by P-1'ing. Set your PFactor line to have the "Factored To" value to be no more than the last column.

[CODE]+----------+---------------+--------+
| Exponent | BitLevel | FactTo |
+----------+---------------+--------+
| 54911783 | 58.3215560913 | 58 |
| 58910237 | 64.6313400269 | 64 |
| 58726133 | 65.4111557007 | 65 |
| 52733041 | 68.8312835693 | 68 |
| 51247057 | 70.7599105835 | 70 |
| 48609521 | 70.9801712036 | 70 |
| 52303133 | 71.0078811646 | 71 |
| 48533731 | 71.0444488525 | 71 |
| 47254231 | 71.0491561890 | 71 |
| 50556529 | 71.0697021484 | 71 |
+----------+---------------+--------+[/CODE]

ATH 2013-03-29 18:18

Looking at the lifetime stats on the P-1 top producer page:

Top 100 producers have 25,681 successes in 536,894 attempts ~ 4.8% success rate

Top 1000 producers have 34,632 successes in 794,810 attempts ~ 4.4% success rate

Looking at all the 9,834 producers: 37,309 successes in 842,985 attempts ~ 4.4% success rate


Using 4.4% for 218 failed attempts: 0.956^218 ~ 0.0055 % or 1 in 18204.


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