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Old 2009-08-01, 14:35   #13
mdettweiler
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Aug 2007
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Quote:
Originally Posted by Flatlander View Post
How do I do that?
First, you need to make sure the file is in ABC format. A NewPGen file can actually be converted to ABC quite easily without the need for conversion tools: for example on Sierp. base 3, you'd simply change the first like of the file to "ABC $a*3^$b+1" rather than the NewPGen header (the thing with all the colons in it).

Next, you need to specify the "number_primes" option as a comment in the file. To do this, you need to change the ABC header to something like this: "ABC $a*3^$b+1 // {number_primes,$a,1}". That tells PFGW that it should stop searching a particular $a value (that is, the k) if 1 prime is found for that value.

At this point, you're all ready to run it through PFGW. Navigate to the PFGW directory through the command prompt and run the following command (or, use WinPFGW and give it the following command line):

pfgw -l name-of-sieve-file.txt

Note that the -l is quite important--without it, PFGW will not log its composite results to a file (in this case, pfgw.out; to change the name, specify the -l option as something like "-lfile.txt" instead).

One note on stopping/restarting with the number_primes option: if you stop and restart, PFGW will "forget" which k's it's stopped searching. It will still pick up exactly where it's left off, but it won't remember to leave out the k's which it's found a prime for prior to the restart. Thus, if you need to restart, you'll have to remove prior-primed k's from the sieve file (be sure to adjust the line # accordingly in pfgw.ini).
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