sr1sieve and big P

barcode · 2007-12-20, 12:57

Just some stupid questions. I have been using newpgen for sometime and have recently been trying out sr1sieve and I have a question.

Is there anyway to specify P1/pmax/P as infinite (i.e. continue until I manually stop the process)? Or is there are reason why it must be specified?

lavalamp · 2007-12-20, 19:19

You could just set it stupidly high, then when you want to stop it use ctrl+c.

As to why it has to be specified, at a guess I'd say that it's to make sure people know what they're doing. A hoop to jump though which forces people to know what they're doing before they do it.

rogue · 2007-12-20, 19:44

Quote:

Originally Posted by barcode

Just some stupid questions. I have been using newpgen for sometime and have recently been trying out sr1sieve and I have a question.

Is there anyway to specify P1/pmax/P as infinite (i.e. continue until I manually stop the process)? Or is there are reason why it must be specified?

Send an e-mail to Geoff. It would probably be fairly easy to remove the requirement, although he would probably set it to some reasonable limit since memory allocated for the sieve is dependent upon max p.

mdettweiler · 2007-12-21, 04:10

srsieve will, if you don't enter a pmax, by default choose a pmax of pmin+4T (4e12). I'm sure that it wouldn't be hard to produce similar functionality in sr1sieve; however, as lavalamp suggested, you could always just set an arbitrarily high value manually. All you have to do is add a "-P x" flag to the command line when you launch sr1sieve (x in my example represents your arbitrarily high pmax). I used 1e12, i.e. 1T, once recently when I was doing a relatively small sieving job with sr1sieve, though you could always set that to a higher value if you expect to need to go higher than 1T. For example, you could use 1e15, which would be the same as 1P--which is higher than any individual siever would likely ever want to undertake, so that should give you plenty of headroom. (The only projects that I know of that have ever gone up that high are Riesel Sieve and PSP, both of which have quite a lot of collective power thrown on their sieves.)

barcode · 2007-12-21, 08:34

Thanks for all the pointers. Setting an absurdly high pmax is what I did in the end (it should keep my PC busy over Christmas anyway).

geoff · 2007-12-27, 04:05

Quote:

Originally Posted by barcode

Is there anyway to specify P1/pmax/P as infinite (i.e. continue until I manually stop the process)? Or is there are reason why it must be specified?

The main reason that it must be specified rather than using a default value is that sr1sieve was derived from sr5sieve wheich was designed for distributed sieving. A default value for pmax in sr5sieve would usually mean sieving past the end of your reserved range and result in wasted work.

I will add a default value for pmax in a future version of sr1sieve, probably pmin+4e12 as in srsieve, unless someone has a better suggestion.

2007-12-20, 12:57	#1
barcode Jan 2003 2·3² Posts	sr1sieve and big P Just some stupid questions. I have been using newpgen for sometime and have recently been trying out sr1sieve and I have a question. Is there anyway to specify P1/pmax/P as infinite (i.e. continue until I manually stop the process)? Or is there are reason why it must be specified?

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2007-12-20, 19:19	#2
lavalamp Oct 2007 Manchester, UK 1,373 Posts	You could just set it stupidly high, then when you want to stop it use ctrl+c. As to why it has to be specified, at a guess I'd say that it's to make sure people know what they're doing. A hoop to jump though which forces people to know what they're doing before they do it.

2007-12-21, 04:10	#4
mdettweiler A Sunny Moo Aug 2007 USA 1100010010100₂ Posts	srsieve will, if you don't enter a pmax, by default choose a pmax of pmin+4T (4e12). I'm sure that it wouldn't be hard to produce similar functionality in sr1sieve; however, as lavalamp suggested, you could always just set an arbitrarily high value manually. All you have to do is add a "-P x" flag to the command line when you launch sr1sieve (x in my example represents your arbitrarily high pmax). I used 1e12, i.e. 1T, once recently when I was doing a relatively small sieving job with sr1sieve, though you could always set that to a higher value if you expect to need to go higher than 1T. For example, you could use 1e15, which would be the same as 1P--which is higher than any individual siever would likely ever want to undertake, so that should give you plenty of headroom. (The only projects that I know of that have ever gone up that high are Riesel Sieve and PSP, both of which have quite a lot of collective power thrown on their sieves.)

2007-12-21, 08:34	#5
barcode Jan 2003 22₈ Posts	Thanks for all the pointers. Setting an absurdly high pmax is what I did in the end (it should keep my PC busy over Christmas anyway).