Loading ...
Sorry, an error occurred while loading the content.

Re: [PrimeNumbers] ECM record!

Expand Messages
  • 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 1 of 3 , Aug 1, 2003
    • 0 Attachment
      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
    Your message has been successfully submitted and would be delivered to recipients shortly.