What is Prime95 ? - Page 2

QuintLeo · 2003-08-02, 17:22

If we *knew* what the next biggest Mersenne Prime number was, we wouldn't be running this program.

There are MANY Mersenne numbers - only a very few of them are prime - and it takes a modern computer quite a bit of CPU processing time to check even ONE Mersenne number to determine if it is Prime.

Sometimes a Mersenne number will have a very small factor, so it doesn't take very long to determine that it is NOT a prime. Sometimes it doesn't. In either case, once the program finishes checking a number, it will report the results and start checking the next number in it's que.

dsouza123 · 2003-08-02, 17:55

The prime number that is being searched for is the next Mersenne prime number.

The way the search runs is, mersenne numbers (2^P) - 1,
(2^P) -1 where P is a prime number, are tested to see if the mersenne number is also prime
example 2^3 - 1, P = 3 and is prime, 7 is the mersenne number's value and is also prime so (2^3) - 1 is a Mersenne prime number.

So using various primes P (roughly in order) each is tested to see if (2^P) -1 is also prime.
If so then the discovery is checked, if correct then announced, and eventually the prizes given.

Purpose is to advance the state of mathematics, computational math, and efficiently use computer resources. About 99% of the time a computer is idle while running, using Prime95 to advance math makes productive use of the otherwise wasted computer resources.

smh · 2003-08-02, 19:42

Quote:

then did anyone discover this prime number they r all searching for

In a way yes.

GIMPS found a new record prime 5 times already.

Take a look at the 10 largest primes taht are know today:

[code:1]
----- -------------------------------- ------ ---- ---- --------------
rank description digits who year comment
----- -------------------------------- ------ ---- ---- --------------
1 2^13466917-1 4053946 G5 2001 Mersenne 39?
2 2^6972593-1 2098960 G4 1999 Mersenne 38
3 2^3021377-1 909526 G3 1998 Mersenne 37
4 2^2976221-1 895932 G2 1997 Mersenne 36
5a 130816^131072+1 670651 g308 2003 Generalized Fermat
6f 3*2^2145353+1 645817 g245 2003
Divides Fermat F(2145351), GF(2145351,3), GF(2145352,5),
GF(2145348,6), GF(2145352,10), GF(2145351,12)
7f 62722^131072+1 628808 g308 2003 Generalized Fermat
8a 2232007*2^1490605-1 448724 L4 2003
9 2^1398269-1 420921 G1 1996 Mersenne 35
10c 1540550^65536+1 405516 GF2 2003 Generalized Fermat
[/code:1]

As you can see, 1,2,3,4 and 9 are all mersenne primes, and all were discovered by someone running Prime95

(so the number you are looking for is a new largest primenumber)

os008 · 2003-08-02, 20:08

THANKS very much (smh and dsouza123) for this explanation ... the equation dsouza wrote helped understand what the mersenne numbers r which really cleared things up :) ... and good luck with the search.

smh · 2003-08-02, 21:26

A nice property of Mersenne numbers is that they consist of all 1's if you write them in binary (base 2)

os008 · 2003-08-02, 22:37

oic ... math have a lot of interesting facts :) ... but i hate it .. i love Structure (planes one of course) and aerodynamics :)

eepiccolo · 2003-08-04, 13:30

Quote:

Originally Posted by os008

oic ... math have a lot of interesting facts :) ... but i hate it .. i love Structure (planes one of course) and aerodynamics :)

That's actually interesting to me that you don't like math, because of the few aerospace engineer friends I have, all but one of them hate math. It seems to be an epidemic amoung you guys. ;)

os008 · 2003-08-04, 15:54

America ? (Location i mean) ?

eepiccolo · 2003-08-04, 17:00

Yeah, the friends of mine graduated either from University of Maryland or from Virginia Tech.

2003-08-02, 17:22	#12
QuintLeo Oct 2002 Lost in the hills of Iowa 2⁶·7 Posts	If we knew what the next biggest Mersenne Prime number was, we wouldn't be running this program. There are MANY Mersenne numbers - only a very few of them are prime - and it takes a modern computer quite a bit of CPU processing time to check even ONE Mersenne number to determine if it is Prime. Sometimes a Mersenne number will have a very small factor, so it doesn't take very long to determine that it is NOT a prime. Sometimes it doesn't. In either case, once the program finishes checking a number, it will report the results and start checking the next number in it's que.

2003-08-02, 17:55	#13
dsouza123 Sep 2002 2·331 Posts	The prime number that is being searched for is the next Mersenne prime number. The way the search runs is, mersenne numbers (2^P) - 1, (2^P) -1 where P is a prime number, are tested to see if the mersenne number is also prime example 2^3 - 1, P = 3 and is prime, 7 is the mersenne number's value and is also prime so (2^3) - 1 is a Mersenne prime number. So using various primes P (roughly in order) each is tested to see if (2^P) -1 is also prime. If so then the discovery is checked, if correct then announced, and eventually the prizes given. Purpose is to advance the state of mathematics, computational math, and efficiently use computer resources. About 99% of the time a computer is idle while running, using Prime95 to advance math makes productive use of the otherwise wasted computer resources.

2003-08-02, 20:08	#15
os008 Aug 2003 7₈ Posts	THANKS very much (smh and dsouza123) for this explanation ... the equation dsouza wrote helped understand what the mersenne numbers r which really cleared things up :) ... and good luck with the search.

2003-08-02, 21:26	#16
smh "Sander" Oct 2002 52.345322,5.52471 1189₁₀ Posts	A nice property of Mersenne numbers is that they consist of all 1's if you write them in binary (base 2)

2003-08-02, 22:37	#17
os008 Aug 2003 7 Posts	oic ... math have a lot of interesting facts :) ... but i hate it .. i love Structure (planes one of course) and aerodynamics :)

2003-08-04, 15:54	#19
os008 Aug 2003 111₂ Posts	America ? (Location i mean) ?

2003-08-04, 17:00	#20
eepiccolo Dec 2002 Frederick County, MD 101110010₂ Posts	Yeah, the friends of mine graduated either from University of Maryland or from Virginia Tech.