Thread: P-1 discussion View Single Post
 2007-03-25, 21:20 #2 hhh     Jun 2005 373 Posts P-1 is two-staged. First stage: If there is a factor $p$, it will be found if $p-1$ has only factors below B1. Second stage: If there is a factor $p$, it will be found if $p-1$ has only factors below B1, except one which can lie between B1 and B2. How to choose B1/B2? Prime95 calculates (in a very complicated formula) the best factor throughput by taking into account -processor type (I guess), -memory settings (stage 2 needs a lot of mem), -factorworth (how many LLR tests are going to be saved by a factor, that is the final 1 in the Pfactor=... line), -and up to where it has already been sieved (that's the 33: it has been sieved up to 2^33). If you tell him that you sieved up to 2^50, it will tell you that P-1 isn't worth it and that you should directly LLR. If you lower the sieve value, it will raise the bounds. But that's not what one should do. Better it is to have faith in the wisdom of the MASTER, and feed the program the correct values. Tomorrow, the 33 would be a 35, for example, because we will have sieved more. But that dosn't change much. Still questions? Yours H. PS. there is a way to chose the bounds manually, by a command i won't tell you, but which is far from secret. H.