Christoph- Jeff is right, the largest prime p we need to precompute is p < sqrt(2^31), so in total we'd get away with a dozen kB of RAM. The only prime in the factorization we'd not catch this way can be retrieved later on during the factorization.
But I agree with you that's it's not really worth the effort. Cheers -Andreas On 02:39 Tue 11 Feb , Christoph Niethammer wrote: > sqrt(2^31)/log(sqrt(2^31))*(1+1.2762/log(sqrt(2^31)))/1024 * 4byte = > 18,850133965051 kbyte should do it. ;) > Amazing - I think our systems are still *too small* - lets go for MPI with > int64 types. ^^ > > ----- Ursprüngliche Mail ----- > Von: "Jeff Squyres (jsquyres)" <jsquy...@cisco.com> > An: "Open MPI Developers" <de...@open-mpi.org> > Gesendet: Dienstag, 11. Februar 2014 01:32:53 > Betreff: Re: [OMPI devel] Reviewing MPI_Dims_create > > On Feb 10, 2014, at 7:22 PM, Christoph Niethammer <nietham...@hlrs.de> wrote: > > > 2.) Interesting idea: Using the approximation from the cited paper we > > should only need around 400 MB to store all primes in the int32 range. > > Potential for applying compression techniques still present. ^^ > > Per Andreas' last mail, we only need primes up to sqrt(2B) + 1 more. That > *has* to be less than 400MB... right? > > sqrt(2B) = 46340. So the upper limit on the size required to hold all the > primes from 2...46340 is 46340*sizeof(int) = 185,360 bytes (plus one more, > per Andreas, so 185,364). > > This is all SWAGing, but I'm assuming the actual number must be *far* less > than that... > > -- > Jeff Squyres > jsquy...@cisco.com > For corporate legal information go to: > http://www.cisco.com/web/about/doing_business/legal/cri/ > > _______________________________________________ > devel mailing list > de...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/devel > _______________________________________________ > devel mailing list > de...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/devel -- ========================================================== Andreas Schäfer HPC and Grid Computing Chair of Computer Science 3 Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany +49 9131 85-27910 PGP/GPG key via keyserver http://www.libgeodecomp.org ========================================================== (\___/) (+'.'+) (")_(") This is Bunny. Copy and paste Bunny into your signature to help him gain world domination!
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