Thread: lots of large primes View Single Post
 2008-08-15, 14:26 #3 Peter Hackman     Oct 2007 linköping, sweden 22×5 Posts Perhaps the example below helps clarify my observations/questions. I've run it with varying small primes bounds (but always the same tolerance term, 2*int(log(pmax)) and factor base sizes. In my program the ideal seems to be a little above 2000, giving a number of factorizations very close to, sometimes slightly smaller than, the size of the factor base. Each polynomial gives rise to 10 plus or minus 3 trials and I believe the success rate is something like 85-90% (I've no idea how many candidates I'm missing!). What strikes me is the much larger percentage of matches in the first case, and this is a recurring observation. N=27656492312230575123821463511979706363619541782727 smoothness bound 45000, about 2400 primes. smalles prime sieved on: 37. multiplier 3: 1793 polynomials 1311 smooths large prime factorizations 13132 matches 1774 number of relations: 785 multiplier 1: 1575 polynomials 1216 smooths large prime factorizations: 14943 matches: 1277 number of relations: 170 This is really a different topic, but I don't get duplicate polynomials. I generate the a=q*q coefficients by picking a number at random in a small neighborhood of the ideal size and look for the next larger prime number q with q&3=3. I keep a list of the q's and check for duplicates (I've tried hashing, too). For some reason this approach seems to be faster than stepping outwards from the ideal! I'm sure there are better ways, but I haven't seen any discussion of this in the literature.