mersenneforum.org Factoring program
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2003-11-23, 23:38   #1
ET_
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), re-engineered 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^p-1
- prints a status line every 50,000 iterations and whenever a factor is found.

To-do 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.
Attached Files
 factor1b.zip (55.4 KB, 652 views)

 2003-11-24, 07:41 #2 tom11784     Aug 2003 Upstate NY, USA 32610 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?
 2003-11-24, 21:29 #3 ET_ Banned     "Luigi" Aug 2002 Team Italia 113718 Posts Sure... If I understood your question :-P It's an enhancement of the 1 or 7 mod 8 idea. Luigi
 2003-11-25, 02:57 #4 tom11784     Aug 2003 Upstate NY, USA 1010001102 Posts ok ... i don't know why i was thinking that 17 is 3 mod 8

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