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Old 2007-05-26, 09:42   #7
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Jun 2003

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Originally Posted by cheesehead View Post
The efficiency of each choice is proportional to the ratio (chance of finding a factor)/(time to find a factor), so that ratio calculation is the one I use in the following: Prime95 will prefer combination X because 1.0%/10 (.010/10) is greater than 1.3%/15 (.013/15) or 1.5%/16 (.015/16).

Originally Posted by
So how does GIMPS intelligently choose B1 and B2? We use a variation of the formula used in trial factoring. We must maximize:

chance_of_finding_factor * 2 * primality_test_cost - factoring_cost
You cannot define efficiency of P-1 without considering the cost of an LL test.
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