Thread: mtsieve
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Old 2018-02-17, 14:33   #7
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Apr 2003
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Originally Posted by pepi37 View Post
Output is always in pfgw format regardless what switch is used
-f --format=f format of output file (A=ABC, D=ABCD (default), N=NEWPGEN)
( to clarify -extension is always pfgw, but header doesnot match , so srfile cannot process file)
-W option doesnot work
-P value is not working
For fbncsieve -P can be overridden by the program if it detects that you are sieving too deeply. In your example, it decides to sieve no deeper than sqrt(1000000*3^11+1). The message states that after sieving to that value, all remaining terms in the output file are prime. This is the exact same behavior as newpgen.

-W does work, but since the sieving in this example is not very deep, a second worker doesn't have any work as all of the primes tested are tested by the first worker. Try again with a larger n that requires much deeper sieving and you will see that.

-f and --format do work. .pfgw is just an extension. Although the programs formats output as documented, it doesn't change the file extension. I made no guarantees that srfile will be able to process the output from fbncsieve. Is there some reason that you need srfile to read the output from fbncsieve?

I have an update on the performance issue. This version of fbncsieve is still faster than the previous one that only supports a single thread which means that fbncsieve is not impacted. I have not looked at the gfndsieve code yet, but I clearly did something really bad when I ported the code into the framework.
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