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Re: [PrimeNumbers] ECM record!

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  • David Cleaver
    ... OK, so reading through this, and then reading a little at the ECMNET page, located at: http://www.loria.fr/~zimmerma/records/ecmnet.html Is it better to
    Message 1 of 3 , Aug 1, 2003
      Andrey Kulsha wrote:
      >
      > http://listserv.nodak.edu/scripts/wa.exe?A2=ind0307&L=nmbrthry&F=&S=&P=2628
      >
      > A big one!
      >
      > Best wishes,
      >
      > Andrey

      OK, so reading through this, and then reading a little at the ECMNET
      page, located at:
      http://www.loria.fr/~zimmerma/records/ecmnet.html
      Is it better to tackle big numbers like this with Prime95 or ecm-5.0.
      And, how does it count as an ecm record? Does Prime95 run ecm curves on
      numbers, and if so, how do you know what size factors it is looking
      for? Does anyone know which is faster, Prime95 or ecm-5.0 on numbers of
      the mersenne form? Just curious because I was thinking of contributing
      to one of these projects, but wanted to make sure I was contributing as
      much as I can.

      -David C.
    • Sander Hoogendoorn
      ... I did some quick testing on a P4 For stage 1, Prime95 is MUCH faster than GMP-ECM 5 I tried running a few curves with B1=1e6 on M(971) which has no known
      Message 2 of 3 , Aug 1, 2003
        David Cleaver wrote:

        > Is it better to tackle big numbers like this with Prime95 or ecm-5.0.

        I did some quick testing on a P4

        For stage 1, Prime95 is MUCH faster than GMP-ECM 5

        I tried running a few curves with B1=1e6 on M(971) which has no known
        factors (293 digits), and on M(959) which has a few known factors (254
        digits, i didn't spent time looking for 1 or a few more known factors which
        make it a C213).

        Stage 1:

        M(971) Prime95 ~28.5
        GMP-ECM 5 ~102

        M(959) Prime95 ~28.3
        GMP-ECM 5 ~113

        Even though M(959) has known factors, GMP-ECM seems faster running on the
        full number!

        For stage 2 things are a bit different. Prime95 uses a default B2=100*B1
        while GMP-ECM uses a much larger B2 (in my case for B1=1M, B2 was ~839M)

        Using B2=100*B1

        M(971) Prime95 ~15.5
        GMP-ECM 5 ~16.9

        M(959) Prime95 ~15.5
        GMP-ECM 5 ~14

        With the default B2, GMP-ECM needs 75 resp. 64 seconds for 1 curve but has a
        higher chance of finding a factor.

        So only when a numbers has known factors, B2 might be faster with GMP-ECM
        (it is possible to run B1 with prime95 and B2 with GMP-ECM).

        On a P3 or Athlon things might be very different since they don't use the
        SSE2 optimizations in Prime95

        > And, how does it count as an ecm record? Does Prime95 run ecm curves on
        > numbers, and if so, how do you know what size factors it is looking
        > for?

        You can set the bounds youreself in Prime95

        Sander
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