20031123, 23:38  #1 
Banned
"Luigi"
Aug 2002
Team Italia
3×1,619 Posts 
Factoring program
Here it is!
I shared some idea with Andreas Pipp (a forum lurker), reengineered the program a bit adding some 50% boost. Now Factor1 can:  choose start and end bit factoring  show actual bit factoring in real time  use 128 bit unsigned integers  follow the search when a factor is found How it works: just run it form console, enter the exponent to be tested, start bit depth and end bit depth (the program check itself the correct start sizes) What it does:  check primality of the exponent using fermat's Little Theorem, and checks for Carmichael numbers as well.  check for known Mersenne Primes  set k to build a 2kp+1 possible d factor  check d mod 120 to eliminate invalid factors  checks d mod (the first 60 primes) to clear about 60% of d's  compute a powermod to ensure the number doesn't divide 2^p1  prints a status line every 50,000 iterations and whenever a factor is found. Todo list I can use the program as is, but if anyone of you find it useful, I can add the following features:  a save file written every n iterations  a routine to automatically restart the search from a save file  compatibility with worktodo.ini files  timing and stat routines Hope you enjoy it! Luigi P.S. Should it be useful, the program can be transferred to the factorization forum. 
20031124, 07:41  #2 
Aug 2003
Upstate NY, USA
326_{10} Posts 
1 question  well maybe 2
I noticed the line: int mod120[16]={1,7,17,23,31,41,47,49,71,73,79,89,97,103,113,119}; // possible mods of 120 Is this supposed to represent the possible values of the exponent mod120 for the number to be a possible mersenne prime? 
20031124, 21:29  #3 
Banned
"Luigi"
Aug 2002
Team Italia
11371_{8} Posts 
Sure... If I understood your question :P
It's an enhancement of the 1 or 7 mod 8 idea. Luigi 
20031125, 02:57  #4 
Aug 2003
Upstate NY, USA
101000110_{2} Posts 
ok ... i don't know why i was thinking that 17 is 3 mod 8

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