Sieving discussion thread

[jasong]

100M-150M reserved (I'm just going to sieve this)

[gribozavr]

jasong, I'm already sieving 100M-5G. I've reached a point where I can release 100-150M for LLR, I'm just waiting for MooooMoo to become a moderator and setup a thread like "Team drives" in Reisel Prime Search.

[jasong]

Originally Posted by gribozavr

100,000,000 - 5,000,000,000

The second is way too large ;) Will we ever have enough resources for LLR'ing it?

lol, I managed to sieve my range to 1 billion, but the second step required so much memory that the computer started thrashing(did I say that correctly? no matter).

I'm going to try again by doing it in two batches.

As to it being two big, I'm doing it for fun and have no idea what I've gotten myself into in terms of whether or not I can accomplish the task.

It'll be fun to attempt, though. (If it takes more than two weeks, I'll try to find a way to send it back. That will be an interesting problem, as the file at 1 billion p is more than a gig.)

[MooooMoo]

Originally Posted by jasong

lol, I managed to sieve my range to 1 billion, but the second step required so much memory that the computer started thrashing(did I say that correctly? no matter).

I'm going to try again by doing it in two batches.

As to it being two big, I'm doing it for fun and have no idea what I've gotten myself into in terms of whether or not I can accomplish the task.

It'll be fun to attempt, though. (If it takes more than two weeks, I'll try to find a way to send it back. That will be an interesting problem, as the file at 1 billion p is more than a gig.)

Remember to choose the "twin search" on NewPGen, and do not include even k values. For a range of 5G, you should have less than 3 million candidates after sieving to 1 billion

[jasong]

Originally Posted by MooooMoo

Remember to choose the "twin search" on NewPGen, and do not include even k values. For a range of 5G, you should have less than 3 million candidates after sieving to 1 billion

I seem to be making errors left and right, but since there are plenty of other k's for people to sieve in the interim, I'm going to try one last time.

Btw, I'm unreserving 125 billion to 150 billion so I can concentrate on 100 billion to 125 billion.

[jasong]

My range is too big to edit as a text file. I'm considering asking the dude who does prothsieve.com to help me deal with it. He has a huge file too, but he developed a reservation method that would let you download certain ranges.

Btw, if anyone wants to start a website for this, I'd be willing to donate $5 to help pay for it.

[MooooMoo]

Originally Posted by jasong

My range is too big to edit as a text file. I'm considering asking the dude who does prothsieve.com to help me deal with it. He has a huge file too, but he developed a reservation method that would let you download certain ranges.

Btw, if anyone wants to start a website for this, I'd be willing to donate $5 to help pay for it.

Pacionet is working on a website (see "twin prime search?" thread). I don't know what you're talking about for 100 billion to 125 billion though:

- Everything above 100 million (not billion) is available for LLR
- Everything above 5 billion is available for sieving
- We expect to find a twin before 20 billion

[jasong]

Originally Posted by MooooMoo

Pacionet is working on a website (see "twin prime search?" thread). I don't know what you're talking about for 100 billion to 125 billion though:

- Everything above 100 million (not billion) is available for LLR
- Everything above 5 billion is available for sieving
- We expect to find a twin before 20 billion

I think we're dealing with two different definitions of ranges. In one thread 100M-125M actually means 100 billion to 125 billion. I think in this thread 100M-125M means exactly what it says.

I don't like wasting time, so I'm going to do some Riesel Sieve LLRing until we get this straightened out.

In the mean time, I have a 1.75GHz 32-bit Sempron, and would appreciate it if someone would assign me a range that takes about 2 weeks to get down to 2 minutes an n.

Thanks in advance.

[gribozavr]

I use SI prefixes and advice everyone to do so:
1M = 1e6
1G = 1e9
1T = 1e12
Billion is a bit fuzzy: it is defined as 10e9 on short scale, while it is equal to 1e12 on long scale. That's why I prefer not to use this word.

Links:
http://en.wikipedia.org/wiki/SI_prefix
http://en.wikipedia.org/wiki/Long_and_short_scales

[gribozavr]

pacionet,

It is 100,000,000-104,999,999.

[MooooMoo]

Post all discussions about sieving here, in order to avoid confusion.
I've removed all recent posts dealing with sieving, and I put them here.

by biwema (4/16)

Maybe it is better not to go into the top 5000. the list would be flooded and the 250000 bit candidates will fall out of the list soon anyway.

some Data (based on a P4, 3.4 GHz)
sizebits testtime Twins in 100G CPU time of 1 Million candidates
180000 108s 8.6 3.4y
200000 133s 7 4.2y
250000 205s 4.4 6.5y
300000 326s 3.1 10.3y
400000 586s 1.7 18.6y

Test Factoring: also P4, 3.4 GHz (athlon would be fatser)
250000 bits, Range 10G (larger ranges do not take much longer)
limit 10^12; 5449847 candidates left (fit into estimate above)
80 Million / s at 1 T; 33 candidtes removed per second.

Candidates removed in 100 G Range:
-------------removed--fact time
46.66-50 bits: 5.2M 0.36years
50-53.33 bits: 4.2M 3.6years (optimal limit for 100kbit candidates)
53.55-56.66 bits: 3.5M 36years (optimal limit for 300kbit candidates)
56.66-60 bits: 3.9M 360 years (optimal limit for 1Mbit candidates)

I recommend to sieve up to 53 or 54 bits (10Q), assuming you choose a range of about 25G candidates at 180000 or 200000 bits (25 G contain about 2 twins)

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by gribozavr (4/30)

Just an update on sieving progress:
n=195000, kmin=1e8, kmax=5e9, without even k's. Now I'm at p=7.0 trillion, 2,294,824 k's left, sieving rate is 1 k every 1.4 sec.

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by davar55 (5/4)

To Moooomoo: Who will do the double checking of the smaller primes?
The sieving algorithm requires these to be constantly rechecked.

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by gribozavr (5/4)

Please, explain, what do you mean by "smaller primes"?

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by davar55 (5/4)

M1 thru M1000

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by gribozavr (5/4)

I don't think we will be ever doublechacking everything. Maybe, at some point in future, when we gather many participiants, we will check just, say, 5 random numbers from a "chunk" in presieved ranges. If one or more residues will not match, the whole range will be released once more for doublechecking.

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by davar55 (5/4)

The point of sieving is to do multiple tasks at the same time.
Each higher level must re-check all lower levels first.

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by gribozavr (5/4)

Can't really understand what you are talking about. I'm sieving on a Prime Stable computer with NewPGen -- a program which is proven BugFree (TM) with expirience of years. I'm 99.999% sure that sieving hasn't removed even a single number, having found a false factor.

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by biwema (5/5)

NewPGen is safe that it does not remove twin candidtes. There is an option to verify all factors in (almost) zero time.

PRP, LLR could moss twins due to hardware failure. Nevertheless it makes no sense to doublecheck. We don't need to find *all* twins in a range, hence it is more efective to check a new range instead of doublechecking. The calculation time of a candidate is short, so in case of a hardware error only a very small fraction of candidateds are faulty (unlike mersenne numbers, where one fault in one month could destroy the test).

Probability of finding a twin in a range:
my calculations of n=195000 give...
range
k=5 G chance of finding a twin: 31%
k=10 G chance of finding a twin: 52%
k=20 G chance of finding a twin: 77%
k=25 G chance of finding a twin: 84%
k=30 G chance of finding a twin: 89%
k=40 G chance of finding a twin: 95%
k=50 G chance of finding a twin: 97.5%

gribozavr, maybe it makes sense to start a new range of 5G to 25G and merge it to the previous one when it reached the same level.
This only makes sense if the project does no jump to a new exponent before reching 5G.