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"Nothing to see here... (2, Funny)

tygerstripes (832644) | more than 7 years ago | (#16103302)

...Please move along."

That's what /. said when I first clicked the story, anyway. I immediately assumed it had been commandeered for use in US military codes...

</tinfoil hat>

Slow news day? (-1, Troll)

Noxal (816780) | more than 7 years ago | (#16103318)

Who the hell cares? Seriously. Show me someone that cares, and I'll show you someone who needs to get laid.

Re:Slow news day? (2, Funny)

Aladrin (926209) | more than 7 years ago | (#16103534)

I ca... Oh crap.

This is like playing tabletennis alone (2, Insightful)

LiquidCoooled (634315) | more than 7 years ago | (#16103338)

They say that they are on a winning streak and that lightening strikes twice etc, well I just say they are continuing running a program which can handle large numbers.
The longer they run it the more they will find.
They are getting all the records because noone else is "trying" as hard.

Good luck that they get the 10million digits, but its just a pissing competition as far as I can see.
They win 100,000 from the EFF for breaking it, but the computational power and time wasted has to be getting close to that itself.

Re:This is like playing tabletennis alone (1)

NotQuiteInsane (981960) | more than 7 years ago | (#16103439)

> Good luck that they get the 10million digits, but its just a pissing competition as far as I can see.
Yeah, all that computing power could be doing something useful, like say, helping the NSA and other TLAs break encryption keys. Probably under the cover story that they're 'searching for extraterrestrial intelligence'... Yeah, like that'll ever happen.. :P

Re:This is like playing tabletennis alone (1)

QuantumG (50515) | more than 7 years ago | (#16103459)

Or, ya know, estimating protein folding, something that could contribute to medical research and thus save lives one day.

Re:This is like playing tabletennis alone (1)

$RANDOMLUSER (804576) | more than 7 years ago | (#16103621)

I've been running prime95 on my Windows machine for 6 or 7 years. I think it's WAY more useful and productive than SETI, and I'm not willing to use my spare cycles to enrich other peoples patent portfolios. I think being able to produce a nine million digit prime number by memorizing eight digits is a pretty cool thing.

Re:This is like playing tabletennis alone (1)

LehiNephi (695428) | more than 7 years ago | (#16104790)

I can't argue about the novelty of being able to "produce a nine million digit prime number by memorizing eight digits", but I'll take issue with your comment about the patent portfolio. Stanford have stated [stanford.edu] that they'll make the results available to everyone.

I run Folding@Home since my computers are on 24/7 anyway--and if it leads to a cure for cancer/leukemia/Hodgekins'/alsheimer's/whatever-ot her-cancer-related-disease, I won't mind if someone makes money off producing the cure.

Re:This is like playing tabletennis alone (0)

Anonymous Coward | more than 7 years ago | (#16105623)

How does making the results available to everyone prevent them from getting patents?

Re:This is like playing tabletennis alone (1)

BKX (5066) | more than 7 years ago | (#16105828)

Prior Art

Re:This is like playing tabletennis alone (1)

freakmn (712872) | more than 7 years ago | (#16106200)

Prime95 is so outdated. Try the latest in prime number finding: The Prime Number Pooping Bear [surfeu.fi] . I won't believe this number until the bear confirms it for me.

Re:This is like playing tabletennis alone (1)

fatphil (181876) | more than 7 years ago | (#16103937)

[Note - if I appear partisan, it's because I'm a prime-hunter myself]

I don't think that it's fair to say that no-one is trying as hard, as many people are, it's just a matter of quantity of effort, rather than quality of effort. GIMPS is huge (and maintains a momentum because of that - people join it because it's the biggest).

So electricity-wise, you're not just right, you're so right that you're completely wrong! (Did that make sense?) It we pretend that on average they have been running 50000 machines for the last 10 years, this prize amounts to 0.2c per machine year.

FatPhil

Woo Hoo! (3, Funny)

nystagman (603173) | more than 7 years ago | (#16103355)

2 ^ 32,582,657 - 1th post. Eventually...

int? (0)

Anonymous Coward | more than 7 years ago | (#16103414)

hmmm... that's not gonna fit in an int is it?

That's amazing! (5, Funny)

johnfink (810028) | more than 7 years ago | (#16103419)

I have the same combination on my luggage!

Re:That's amazing! (0)

blinder (153117) | more than 7 years ago | (#16103497)

darn it, no mod points. i did, however, post a pleading for mod points in my journal, for this post. yes, an old joke, but very funny... especially in this context.

Biggest non-Mersenne prime? (2, Interesting)

tepples (727027) | more than 7 years ago | (#16103460)

So what's the biggest known prime number that's not a Mersenne number? Wikipedia's "Prime number" article [wikipedia.org] states that it's a prime Proth number [wikipedia.org] , but what about the biggest prime that's not of any special form? Or is that illegal [wikipedia.org] to discuss on Slashdot, a server on US soil?

Re:Biggest non-Mersenne prime? (2, Insightful)

Anonymous Coward | more than 7 years ago | (#16103765)

what about the biggest prime that's not of any special form?

I'd tell you, but it doesn't fit in the comment limits.

Re:Biggest non-Mersenne prime? (2, Funny)

nacturation (646836) | more than 7 years ago | (#16105003)

I'd tell you, but it doesn't fit in the comment limits.

Just list the factors... I'm sure we can do the math ourselves.
 

Not of a special form? (1)

benhocking (724439) | more than 7 years ago | (#16103837)

How do you define a prime number that's not of a special form? Wouldn't such a definition make the prime of a special form?

Compressibility (1)

tepples (727027) | more than 7 years ago | (#16103963)

How do you define a prime number that's not of a special form?

I was operating under the assumption that consensus among pure mathematicians creates the list of formulae known to produce a lot of large prime numbers from a few arguments. These include Mersenne numbers (where Mersenne(n) = 2^n - 1 for all prime n) and Proth numbers (where Proth(k, n) = k*2^n + 1 for all odd k < 2^n). I was looking for primes that aren't as compressible.

A good definition (1)

benhocking (724439) | more than 7 years ago | (#16104116)

Although I could argue that a lack of compressibility might be special. ;) Still, regardless of definitions, it would be interesting to find such a prime, or to postulate about their existence. Is there a postulate that such a prime must exist? Is it possible that all primes have a certain level of "compressibility"?

Random data followed by an odd integer (1)

tepples (727027) | more than 7 years ago | (#16104298)

Although I could argue that a lack of compressibility might be special.

Kolmogorov complexity [wikipedia.org] is an objective measure of compressibility. However, this measure is not computable.

Still, regardless of definitions, it would be interesting to find such a prime

Finding such a prime is straightforward. Take a block of true random data (which is incompressible by definition), append an odd integer, and then increase that odd integer until primality tests such as ECPP [wikipedia.org] come back true. This is the technique used to find the first prime that may be illegal to publish [wikipedia.org] .

Re:Random data followed by an odd integer (1)

djshaffer (595950) | more than 7 years ago | (#16104463)

I can compress any prime number, given sufficient compute time.

2 => 1
3 => 2
5 => 3
7 => 4

See? 2 is the 1st prime, 3 is the second. Just make sure you haven't missed any as you get to larger primes. As a tradeoff, the compression factor eventually gets very high.

No expert in primes or compressibility, but... (1)

benhocking (724439) | more than 7 years ago | (#16104670)

Truly random data definitely has a chance of being compressible. For example, there's a 1 in 2^50 chance that a random, fair Bernoulli process will generate the string /1{50}/. If I use a biased Bernoulli process, say with p=0.999, I can generate such a string with much better odds. Specifically, there's more than a 95% chance that I'd generate that string, and there's even a 37% chance that I'd generate /1{1000}/, for a string of size 1,000.

I read the piece on Kolmogorov complexity, and although it's theoretically a well-defined measure (given a particular programming language or other form of interpretation), in practice it's doubly exponentially difficult to calculate. I'd have to generate every possible program of size less than n (where n is the actual Kolmogrov complexity) in order to verify that n is in fact the Kolmogrov complexity. Worse yet, for those programs that don't halt (and are of size less than n), I'll have to know that they don't halt. (Despite the well-known issues with the halting problem [wikipedia.org] , this can actually be done trivially for a program of maximum size n if you have a machine of state size 2^n (for a binary language) and a lot of patience.)

Self correction (1)

benhocking (724439) | more than 7 years ago | (#16104869)

Despite the well-known issues with the halting problem, this can actually be done trivially for a program of maximum size n if you have a machine of state size 2^n (for a binary language) and a lot of patience.

Um, that's only true if the machine the program is being run on is limited to n binary states. So, for a true Turing machine, I think that actually calculating the Kolmogorov complexity is not even theoretically possible, unless the "language" specification stipulates a maximum amount of memory to use (perhaps relative to the size of the string being examined). In my opinion, this is not an unreasonable expansion of the definition, however. E.g., if it requires 2 Gigs of RAM and/or hard drive space to compress a 10,000 bit number down to a 1,000 bit program, I'm not sure if it's fair to say that the complexity is only 1,000 bits.

Stars die before halting is solved (1)

tepples (727027) | more than 7 years ago | (#16104943)

If I use a biased Bernoulli process, say with p=0.999, I can generate such a string with much better odds.

I was operating under the assumption of a fair Bernoulli process. In the case of something in any way biased, the device driver will likely convert it to a lower-bandwidth fair Bernoulli process by hashing blocks of raw data and returning one output bit for several raw bits.

(Despite the well-known issues with the halting problem, this can actually be done trivially for a program of maximum size n if you have a machine of state size 2^n (for a binary language) and a lot of patience.)

"A lot of patience"? Living organisms have little patience in this universe. True, halting is computable for linear bounded automata, but not in the human lifetime or even in the lifetime of the universe for a reasonably sized program string. By 10^15 years [wikipedia.org] , it is expected that even the stars will die, providing no more energy to run the computation.

Re:A good definition (1)

flooey (695860) | more than 7 years ago | (#16105488)

Still, regardless of definitions, it would be interesting to find such a prime, or to postulate about their existence. Is there a postulate that such a prime must exist?

There are infinite primes, we know that. Whether every single prime can fit into some kind of classification, though, we don't know. It's conceivable that there might be, but it seems incredibly unlikely, especially given things like the classification of all finite simple groups (most of which fall into a few neat categories and then there are a set of them that don't fit any known categorization).

Re:Not of a special form? (1)

Ed_Pinkley (881113) | more than 7 years ago | (#16104318)

How about this: What is the largest known prime number where all previous prime numbers are also known?

Ed

Might be arbitrary enough (1)

benhocking (724439) | more than 7 years ago | (#16104690)

That might be arbitrary enough to qualify as non-special since it will only be "special" for a limited time.

FTA (1)

hansamurai (907719) | more than 7 years ago | (#16103476)

Perfectly Scientific, Dr. Crandall's company which developed the FFT algorithm used by GIMPS, will make a poster you can order containing the entire 9.8 million digit number. It is kind of pricey because accurately printing an over-sized poster in 1-point font is not easy!

And to think, all I had was a Ghostbusters poster when I was growing up.

You know what would be funny? (1)

UbuntuDupe (970646) | more than 7 years ago | (#16103499)

If they announced finding a new large prime number, and then later realized the number was even, and they hadn't noticed that. (I know, this one is one less than a power of two, but just hypothetically.)

Re:You know what would be funny? (3, Funny)

x2A (858210) | more than 7 years ago | (#16103668)

Or when converted to binary, it turned out to be an mp3 of the latest song from [insert-RIAA-label], and so they banned distribution of it :-p

Re:You know what would be funny? (4, Informative)

kestasjk (933987) | more than 7 years ago | (#16103994)

I know that was a joke, but this gives the impression that this number in binary is a long stream of 1's and 0's.

Seeing as 2^n is [1 followed by n 0's] in binary, and [1 followed by n 0's] minus 1 is [(n-1) 1's], this number in binary will just be 32,582,656 1's, which isn't decodeable as an MP3.

Re:You know what would be funny? (0)

Anonymous Coward | more than 7 years ago | (#16104081)

Actually 1000-1 = 111, not 11.

In other words, it would be 32,582,657 1s.

Re:You know what would be funny? (3, Funny)

r00k123 (588214) | more than 7 years ago | (#16104171)

Could be Bjork...

Re:You know what would be funny? (1, Funny)

thelost (808451) | more than 7 years ago | (#16104189)

really? To me that sounds just like Justin Timberlake's latest stuff :S

Know what... (1)

electrosoccertux (874415) | more than 7 years ago | (#16104472)

Does anyone know how these numbers get parsed out? I wonder if we are using the right formulas? As in I wonder if thinking in a different base number (2?) could help us find a much more precise formula for finding this? This prime was pretty simple-- a couple million 1's in a row. Maybe there's one for a couple million 10's in a row?

Come on there (1)

FoamingToad (904595) | more than 7 years ago | (#16104518)

I hope you're not suggesting that anything ending in a zero, in any counting system, could ever be a prime?

Prime Base (0)

Anonymous Coward | more than 7 years ago | (#16108712)

In any prime base, 10 is a prime number.

Re:Know what... (1)

Chris_Jefferson (581445) | more than 7 years ago | (#16104599)

After reading your comment, I can't really say anything other than.. go do some university level maths courses, and come back.

Basically, mersenne primes are of the form (2^p)-1, where p is a prime. The reason that these numbers seem to keep turning up as really big primes is that there is a very special test which checks if just this type of number is prime. The Mersenne project is searching it's way through all possible candidates to see if it can find some big primes.

Re:You know what would be funny? (1)

Cragen (697038) | more than 7 years ago | (#16105116)

Silly question (cuz IANAM): Are most (many, few or all) binary numbers that have all 1's in the number prime? Just curious. Cragen

Re:You know what would be funny? (0)

Anonymous Coward | more than 7 years ago | (#16106030)

Silly question (cuz IANAM): Are most (many, few or all) binary numbers that have all 1's in the number prime? Just curious. Cragen


A vanishingly small percentage

Re:You know what would be funny? (1)

Meostro (788797) | more than 7 years ago | (#16106155)

A Mersenne number is exactly what you're talking about, a long string of binary 1's.

Mersenne numbers are of the form 2^N - 1, which is essentially a binary string of N consecutive 1's. For example, the tenth Mersenne number - aka M(10) - is 2^10 - 1, which is 1023. The binary representation of 1023 is 1111111111.

The answer to your question is on the GMPS homepage [mersenne.org] :

When looking at the exponents, we expect only 1.78 Mersenne primes between powers of two, and prior to 2003, a maximum of 3 Mersenne primes were found between powers of two. The last 5 Mersenne prime exponents all fell between 224 and 225 -- and we haven't finished testing all the exponents in that range!

So Mersenne primes are very rare numbers. The only reason these primes are so insanely large is that we have efficient* methods of primality testing for numbers of certain special forms. It would be incredibly difficult to conclusively prove primality for 2^32,582,657 - 473** instead, since it's not of the same special form.

* - Efficient is a relative term - this number took hundreds of CPU hours to test for primality. From the same page, it took 6 days on a system "using 16 Itanium2 1.5 GHz CPUs" to confirm the results. For arbitrary 9 million digit numbers however, it would probably take centuries to test primality conclusively, even using current state-of-the-art methods and massive supercomputers.

** - This could be divisible by 3 for all I know, it's very unlikely that it is prime.

Or... (1)

mustafap (452510) | more than 7 years ago | (#16104148)

>Or when converted to binary, it turned out to be an mp3 of the latest song from [insert-RIAA-label]

How about if I released it as a record? Would it then become illegal?

I can't believe it would sound any worse than the rubbish kids are listening to today :o)

Re:You know what would be funny? (1)

Billosaur (927319) | more than 7 years ago | (#16103775)

If they announced finding a new large prime number, and then later realized the number was even, and they hadn't noticed that.

Even funnier -- they name it "Optimus."

It's nice to see, but... (1)

NotQuiteInsane (981960) | more than 7 years ago | (#16103525)

... what possible applications do Mersenne primes of this size have? Is this just some big 'penis envy' thing, or are there actually uses for these?
I mean, Dnet have pretty much proved that any encryption key less than 64 bits is hopelessly insecure (ISTR they're working on 72 bits at the moment), and they did the Optimal Golomb Rulers search, but what possible use does all this stuff have? Are we just looking for things that are neat, but have no use in the real world?
Folding@Home is still pretty neat though - the whole "use your spare CPU cycles to (potentially) find cures for various nasty things" concept is pretty neat, and no-one can say that saving lives isn't worth spending a few clock cycles on.
SETI@Home I'm still not sure about. Yes it would be nice to find 'intelligent' creatures on other planets, but what are we going to do if we find them? Chances are they're going to be at least a few light-years away, so the round-trip times for radio signals are going to be pretty severe...

Re:It's nice to see, but... (1)

boyfaceddog (788041) | more than 7 years ago | (#16103591)

Sometime in the future this too will pay off. Hope for the best and keep looking for new stuff.

Re:It's nice to see, but... (2, Informative)

Ruzty (46204) | more than 7 years ago | (#16105050)

Folding@Home is still pretty neat though - the whole "use your spare CPU cycles to (potentially) find cures for various nasty things"

I think you should have said:
Folding@Home is still pretty neat though - the whole "use your spare CPU cycles to (potentially) find cures for various nasty things and enrich the patent portfolios of drug manufacturers"

HTH HAND
-R

Re:It's nice to see, but... (1)

NotQuiteInsane (981960) | more than 7 years ago | (#16105714)

Point taken. Well played, sir.

At least finding ETs doesn't involve enriching some MegaHuge PharmaCo's patent portfolio...

Re:It's nice to see, but... (0)

Anonymous Coward | more than 7 years ago | (#16105894)

40 years ago there was no concievable use for primes at all...

Help (-1)

DaFrog (703113) | more than 7 years ago | (#16103529)

I thought that all numbers in the form 2^n -1 are prime - If I am correct, what's so new about this number? -Nicolas

Re:Help (0)

Anonymous Coward | more than 7 years ago | (#16103619)

Um, try that with n=4, and you'll see that your assumption isn't correct...!

Re:Help (1)

quaker5567 (841639) | more than 7 years ago | (#16103620)

2^4-1=15

Re:Help (0)

Anonymous Coward | more than 7 years ago | (#16104293)

Exactly. And 15 is divisible by 2.4 and 6.25, silly people.

Re:Help (1)

Iwanowitch (993961) | more than 7 years ago | (#16103623)

Try n=8.

Re:Help (1)

knightmad (931578) | more than 7 years ago | (#16103630)

That is wrong for n=4. 2^4-1 = 16-1 = 15 = 3 * 5 Somehow, somewhere there is a math teach spinning on his/her grave right now.

Re:Help (0)

Anonymous Coward | more than 7 years ago | (#16103637)

2^4 - 1 = 15 = 3*5.

Re:Help (1)

TadMSTR (996071) | more than 7 years ago | (#16103649)

Actually no. Not all numbers in the form of 2^n-1 are prime. There are only 44 known numbers in that form that are prime.

Re:Help (1)

Will2k_is_here (675262) | more than 7 years ago | (#16103653)

Try n=4

Re:Help (1)

Will2k_is_here (675262) | more than 7 years ago | (#16103671)

Ha Ha!

Hey everyone! Let's massacre the parent! Bonus karma points to the one who can shoot down the suggestion the best!

Re:Help (1)

Veetox (931340) | more than 7 years ago | (#16103888)

Um, how about, RTFA? ... The third link gives you a breakdown of the history.

Re:Help (1)

Will2k_is_here (675262) | more than 7 years ago | (#16104113)

RTF Post. I was referring to the parent who thought all numbers of the form 2^n-1 were prime. Naturally, slashdotters ate him up and spit him out.

I say bonus karma points to this guy:
http://slashdot.org/comments.pl?sid=196548&cid=161 03985 [slashdot.org]

Re:Help (1)

Veetox (931340) | more than 7 years ago | (#16106328)

I was responding exactly as you requested - The parent had missed the link "Marsenne prime", which provides an article explaining that some 2^n-1 numbers are not primes and who proved what. The original post already provided Mr. "Help" with the info he needed. Don't worry - but I'm sure I didn't even need to point that out; you've made him feel plenty stupid already.

Re:Help (1)

tygerstripes (832644) | more than 7 years ago | (#16103656)

Not so, I'm afraid [wikipedia.org] . All Mersenne primes are one less than a number which is 2^(prime) - but the converse is not necessarily true.

Re:Help (0, Redundant)

Beached (52204) | more than 7 years ago | (#16103661)

2^4-1 = 15 = 3*5 Not prime

Re:Help (15, 63, ...) (0)

Anonymous Coward | more than 7 years ago | (#16103663)

There are various reaons to think that numbers of the form 2^n-1 are a good place to look for primes, but they are certainly not all primes. Here are the first counter examples:

2^4 - 1 = 16 - 1 = 15 = 3*5
2^6 - 1 = 64 - 1 = 63 = 3*3*7

Re:Help (0)

Anonymous Coward | more than 7 years ago | (#16103664)

2^4 - 1 = 15 = 5 * 3

Re:Help (0, Redundant)

knewter (62953) | more than 7 years ago | (#16103702)

I almost feel silly doing this...

2^4=16
16-1=15
15=3x5

Re:Help (0, Redundant)

Halo- (175936) | more than 7 years ago | (#16103790)

I thought that all numbers in the form 2^n -1 are prime - If I am correct, what's so new about this number? -Nicolas

Nope, most of them aren't:
(2^3)-1 = 8 - 1 = 7 (prime)
(2^4)-1 = 16 - 1 = 15 (not prime, 3, 5)
(2^5)-1 = 32 - 1 = 31 (prime)
(2^6)-1 = 64 - 1 = 63 (prime)
(2^7)-1 = 128 - 1 = 127 (prime)
(2^8)-1 = 256 - 1 = 255 (not prime, 3, 5)
etc..

Re:Help (0)

Anonymous Coward | more than 7 years ago | (#16104184)

> (2^6)-1 = 64 - 1 = 63 (prime)

7*9 = 63

Re:Help (1)

MMC Monster (602931) | more than 7 years ago | (#16104229)

How about:
Prime1*Prime2-2? (so long as neither one of them is '2')

Re:Help (2, Insightful)

FhnuZoag (875558) | more than 7 years ago | (#16104689)

5*7-2 = 33 = 3*11

Trust me. If it was this easy, we'd have heard of it long ago.

Re:Help (1)

jizziknight (976750) | more than 7 years ago | (#16104772)

Nope.
7 * 5 = 35
35 - 2 = 33
33 = 3 * 11

2 * 5 = 10
10 - 2 = 8
8 = 2 * 4

7 * 11 = 77
77 - 2 = 75
75 = 5 * 15

Just to cite a few.

Re:Help (1)

Wooloomooloo (902011) | more than 7 years ago | (#16104246)

63 isn't prime.

*ahem* (1)

DiamondGeezer (872237) | more than 7 years ago | (#16107587)

(2^6)-1 = 64 -1 = 63 = (9 * 7) (not prime)

Re:Help (2, Informative)

publius1234 (615205) | more than 7 years ago | (#16103804)

Mersenne primes are simply primes that have this form, but not all numbers that have this form are prime. For example, 15 = 2^4 -1 and is not prime.

Also, for a number to be a Mersenne prime, the 'n' from 2^n-1 must be prime (according to Mathworld [wolfram.com] ).

Re:Help (1)

wild_berry (448019) | more than 7 years ago | (#16104391)

Mod parent up: poster explains what conditions are required for a Mersenne-form prime.

Re:Help (0, Redundant)

FhnuZoag (875558) | more than 7 years ago | (#16103843)

Good lord, no.

Take 2^4 - 1 = 15 = 3 * 5

Re:Help (2, Informative)

fatphil (181876) | more than 7 years ago | (#16103985)

If a divides n, then 2^a-1 divides 2^n-1.
So for 2^n-1 to be prime, n itself must be prime.

Quick proof - consider the values of 2^i modulo (2^a-1) for i=0..n,
You'll notice that 2^0 == 2^a == 2^(2a) == .... 2^((n/a)*a) == 1.
i.e. 2^n-1 == 0 (mod 2^a-1)

Note, however, that it's a necessary condition, but is not sufficient.
There are plenty of prime p such that 2^p-1 is not prime.

See http://www.primepages.org/ [primepages.org]

FatPhil

Re:Help (1)

Kennego (963972) | more than 7 years ago | (#16104194)

No power on Slashdot so great as the need to correct others' mistakes.

Ok, to actually be helpful here instead of being the 16th person to say 15 isn't prime (seriously, you should all be marked redundant) maybe the parent was thinking of 2^(2^n)+1, which is a Fermat Prime [wikipedia.org] . Unfortunately, not even Fermat Primes are actually prime, Fermat just thought they were when he discovered them.

How to you compute? (0)

Anonymous Coward | more than 7 years ago | (#16103595)

Seriously.. how do you compute? I want to check for my self.

Expand it yourself (3, Informative)

Coppit (2441) | more than 7 years ago | (#16103875)

If you want to expand the number on your machine, run this:

perl -Mbignum -e 'print 2**32582657 - 1'

If it takes too long for you, you can also have perl print an approximation:

perl -e 'print 2**32582657 - 1'

Re:Expand it yourself (1)

B5_geek (638928) | more than 7 years ago | (#16104397)

For real fun add the 'time' command to benchmark your PC's

Re:Expand it yourself (0)

Anonymous Coward | more than 7 years ago | (#16105510)

For real fun add the 'time' command to benchmark your PC's

Don't leave us hanging. Benchmark our PC's what?
 

Re:Expand it yourself (1)

Pharmboy (216950) | more than 7 years ago | (#16104840)

I just wrote a lazy hack to get a list of primes
#!/usr/bin/perl
for ($x=1;$x>0;$x++){
  if(`factor $x|grep '$x: $x'`){
    open(LOG,">>log.txt");
    print LOG "$x\n";
    close(LOG);
  }
}
It's running in the background on my home linux router, an older AMD XP 2700+. Already up to 334157 and the load is only 2.50. Wonder how long it will take until I get to 2^32582657? ;)

Re:Expand it yourself (1)

dylan_- (1661) | more than 7 years ago | (#16104917)

I suspect you'll run out of disk space first! :-) Out of curiosity, what filesize and prime are you at now?

Re:Expand it yourself (1)

Pharmboy (216950) | more than 7 years ago | (#16104975)

Good point! Up to 461207 and a 256k log file. Its on a smaller partition, but if I have to, I can change the value of the first $x to the last prime, and move it over to another partition. Got almost a terrabyte total on the machine, and half of it free.

Re:Expand it yourself (1)

Pharmboy (216950) | more than 7 years ago | (#16106295)

To follow up: Found 141,739 primes, the largest being 1,895,693 before I decided I needed the CPU cycles for something else. (one prime for every 13.3745... numbers). Log file is about 1mb. It took about two hours to get to that number. Might take a little longer to get to a new record. ;)

Then, all i have to do is edit the executable file and put $x=(1895693 +1) to pick up where I left off.

Re:Expand it yourself (1)

crownrai (713377) | more than 7 years ago | (#16107289)

Don't you mean put "$x=(1895693 +2) "?

You're not checking even numbers are you?

Re:Expand it yourself (1)

Pharmboy (216950) | more than 7 years ago | (#16108341)

um, if you look at the code, I'm checking all numbers. It was a full 30 seconds worth of code. I guess I should have done:
for ($x=1;$x>0;$x=($x+2))
...duh me. Oh well, it has that line NOW.

Re:Expand it yourself (0)

Anonymous Coward | more than 7 years ago | (#16108629)

If you do that, you'll have to manually add 2 to your logfile.

Re:Expand it yourself (1)

FooAtWFU (699187) | more than 7 years ago | (#16105590)

If it takes too long for you, you can also have perl print an approximation:
perl -e 'print 2**32582657 - 1'
Okay. I'll try that. :)
<tom@eh ~ $> perl -e 'print 2**32582657 - 1'
inf<tom@eh ~ $>

Re:Expand it yourself (1)

doti (966971) | more than 7 years ago | (#16106232)

If it takes too long
How long is too long?
I have it running for whole three hours now, still no result.
relevant info from /proc/cpuinfo:
model name : AMD Opteron(tm) Processor 248
cpu MHz : 2193.796
cache size : 1024 KB
bogomips : 4377.80

Pfft. Doesn't stand a chance... (4, Funny)

Mister Impressive (875697) | more than 7 years ago | (#16104025)

Doesn't stand a chance against the one true prime...

OPTIMUS PRIME!

The Actual Number (3, Informative)

neonprimetime (528653) | more than 7 years ago | (#16104038)

View it here [isthe.com] in it's 12mb text form!!!!!!!!

clicks text link... (2, Funny)

imrec (461877) | more than 7 years ago | (#16104040)


    *head explodes*

Awww (1)

The MAZZTer (911996) | more than 7 years ago | (#16104114)

I had just been reading up about the Japanese Wii launch dates and I thought this article title was "New Metroid Prime Found". Blast!

Huh? (1)

gravis777 (123605) | more than 7 years ago | (#16108505)

Okay, I know what a Prime number is, I passed high school. And this number is huge.

My question is, can someone describe to me in SIMPLE terms what a Mersenne prime is?

Do we really do math where we need to discover prime numbers this big? I mean, its like trying to compute pi. I mean, once you take PI out a few decimal places, its as accurate as most people need it. Do we really need super computers that do nothing better with their time than calculate this kind of stuff?

I am sorry if I sound ignorant, but it seems to me that sometimes people just get worked up about stuff that we don't really need. I mean, really, yeah, its cool that we found a prime number this large, but whats the point?
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