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Old 2013-05-25, 16:48   #1
TheMawn
 
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Default How to reserve an exponent?

Hi, folks. I've been trying to read a few threads around here but they're all quite dated and they all seem to refer to ranges of exponents.

If I wanted to pick one specific exponent to work on all the way to the end, how would I go about that? The exponent I want is in the 397,874,000 range (it's for 100,000,000 digits). I've checked the factoring effort and it's only been done up to 65. It doesn't appear to have been reserved (I ran a search excluding reserved exponents and it was there) but if I try to manually get an assignment for it, I get factoring from 265 to 266 and that's it.

I'd like to put my GPU to work for however long to get it to 278 or whatever is appropriate and then get a LL-test going if it doesn't find anything (maybe some P-1 first if that is practical?)

Is there a way to grab that whole exponent and tell everyone to keep their grubby paws off it? :P
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Old 2013-05-25, 17:06   #2
chalsall
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Quote:
Originally Posted by TheMawn View Post
Is there a way to grab that whole exponent and tell everyone to keep their grubby paws off it? :P
One way would be to leverage on Prime95/mprime. Put the desired candidate into the worktodo.txt file, in the form of:
Code:
"Test=[Exponent],[Currently_Factored_To],0"
Then have Prime95/mprime communicate with the server. If the candidate (exponent) in question is not already assigned, you should get an "Assignment ID", which means that you "own" it, and it will appear in your Primenet assignments report. You can then manually submit any TFing and P-1'ing work without risk of losing the assignment.

Three important notes:

1. Assignments from Primenet are only valid for 60 days when done in this manner. However, you can manually extend such assignments using the "Manual Testing -> Extensions" menu on Primenet. Even then the assignment is only valid for 180 days.

2. Pack a lunch for this -- it will take a very long time. Set a reminder to yourself to re-extend the assignment every month.

3. Primenet works on a "trust" system. There is nothing preventing someone else from submitting work for the candidate even though it is assigned to you. This doesn't happen often, but it has happened (and occasionally still does happen) -- although very rarely on such high candidates. Be aware.
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Old 2013-05-25, 20:08   #3
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Try 332M range if you want, that is 100M prime, You might want to PM Uncwilly if you want a number... and I would suggest going to 79 or 80 bits. Even more, if you wish.

Oh yes on what chalsall said... it will probably take a LONG time unless you multithread it on more than one cpu.
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Old 2013-05-25, 20:13   #4
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"Test=[Exponent],[Currently_Factored_To],0" I put this in my worktodo.txt for prime95.exe, and it will tell the server to reserve it for me, though it won't actually do any work? It seems a bit backwards to what I thought the system did, i.e. ask for work, get it reserved and THEN automatically write it into worktodo.

...

I'm glad you mentioned this would take a very long time because my first guess was around 2 months, but I think I lost a zero somewhere because my new estimate is about 500 days (I read somewhere the algorithm is O(N2LogN and N is seven times larger than the stuff I am testing now (that takes 11 days, give or take).

Thanks for the info on reserving an exponent. I might do that at a later date but with a more reasonable exponent.


I thought there was a realistic chance at getting a 100-million digit prime number but now that I've properly considered one exponent it looks like we're maybe 6 or 7 years away yet.
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Old 2013-05-25, 20:22   #5
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Out of innocent curiosity I want to see how long the actual factoring would take so I went and got this assignment from primenet:

Factor=4A9A69278DFBDB7DD0CFE58F82E8F016,397874803,65,66

The assignments I get from GPU72 are all look like:

Factor=N/A,65726147,71,72


It seems the only difference is the huge Hex String is replaced by N/A. What is the meaning of that particular argument?
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Old 2013-05-25, 20:39   #6
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Quote:
Originally Posted by TheMawn View Post
It seems the only difference is the huge Hex String is replaced by N/A. What is the meaning of that particular argument?
That "huge Hex String" is the MD5 "Assignment ID".

The "N/A" is a known replacement, meaning "Not Applicable". It tells Prime95/mprime not to try to ask for an AID.
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Old 2013-05-26, 05:55   #7
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Quote:
Originally Posted by TheMawn View Post
so I went and got this assignment from primenet:

Factor=***********,397874803,65,66
That is a very short assignment about 1/2 hour on a 1 GHz core.
To do the LL test is 7,578 GHz-days
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Old 2013-05-26, 06:58   #8
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Quote:
Originally Posted by TheMawn View Post
It seems a bit backwards to what I thought the system did, i.e. ask for work, get it reserved and THEN automatically write it into worktodo.
That _is_ what the system does (though I'd describe it a bit differently) when prime95 contacts PrimeNet for non-LMH work.

My description:

Suppose you're running Prime95 on non-LMH stuff.

1) Either Prime95 automatically contacts PrimeNet at certain time intervals, or you select the Prime95 drop-down menu item to have Prime95 "manually" contact PrimeNet right then.

2a) Prime95 sends to PrimeNet, among other things, messages containing what you have in worktodo.

2b) PrimeNet compares your specified desired amount of work to have queued up with how long Prime95 estimates that your current assignments will take.

3) If, in 2), the former is greater than the latter (i.e., you have less work queued than you specified you want, so you implicitly "ask for work"), then PrimeNet:

3a) selects new assignments according to your specified non-LMH preferences,

3b) reserves (your "get it reserved") those new assignments for you, and

3c) sends Prime95 a message for each new assignment.

4) Prime95 adds the new assignments (according to what PrimeNet has told it in the messages) to your worktodo file (your "automatically write it into worktodo").

- - -

The LMH procedure:

0) _You_ select the new exponents you want to work on, and add a line to worktodo for each of those.

1) same as step 1 above

2a) same as above

2b) skipped until PrimeNet has processed all the (LMH) exponents it didn't already have assigned to you

3) When PrimeNet sees that one or more worktodo lines is/are for exponents you don't already have assigned/reserved, then:

3a) Not done in this case.

3b) and 3c) same as above

4) Instead of adding a new line for the new assignment to your worktodo, Prime95 simply inserts the assignment ID into each line that you had added in step 0.

Last fiddled with by cheesehead on 2013-05-26 at 07:13
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Old 2013-05-26, 14:50   #9
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Quote:
Originally Posted by Uncwilly View Post
That is a very short assignment about 1/2 hour on a 1 GHz core.
To do the LL test is 7,578 GHz-days
@TheMawn
As I've suggested before, Try something in the ~332.2M range...
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