Factoring program

[ET_]

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.

[tom11784]

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?

[ET_]

Sure... If I understood your question :-P

It's an enhancement of the 1 or 7 mod 8 idea.

Luigi

[tom11784]

ok ... i don't know why i was thinking that 17 is 3 mod 8