mersenneforum.org Do you use the breadth-first mode of GMP-ECM?
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 View Poll Results: Do you use the breadth-first mode of GMP-ECM? Yes, frequently 1 3.70% Rarely 6 22.22% (Almost) never 11 40.74% The WHAT? 9 33.33% Voters: 27. You may not vote on this poll

 2011-01-24, 12:47 #1 akruppa     "Nancy" Aug 2002 Alexandria 25×7×11 Posts Do you use the breadth-first mode of GMP-ECM? Do you use the breadth-first mode of GMP-ECM?
 2011-01-24, 13:12 #2 ATH Einyen     Dec 2003 Denmark BA316 Posts You forgot the poll option "breadth-first mode ???" I had to read up on README to see what it was.
 2011-01-24, 13:33 #3 akruppa     "Nancy" Aug 2002 Alexandria 46408 Posts If you consider yourself a regular GMP-ECM user and you've never heard of breadth-first mode, please vote! I'm toying with the thought of removing it, mostly because I don't understand what our main() function does, and wonder how many users would miss it.
2011-01-24, 13:45   #4
R.D. Silverman

Nov 2003

26·113 Posts

Quote:
 Originally Posted by akruppa If you consider yourself a regular GMP-ECM user and you've never heard of breadth-first mode, please vote! I'm toying with the thought of removing it, mostly because I don't understand what our main() function does, and wonder how many users would miss it.
I've never heard of it, but I can guess what it is. When doing
convolutions for products of (p_i - p_j) as p_i and p_j vary over
(different) arithmetic sequences, one can fix p_i and let p_j vary or
vice-versa.

I am guessing that one is referred to as depth-first, and the other

Is my guess close?

 2011-01-24, 13:46 #5 Karl M Johnson     Mar 2010 3·137 Posts From the tarball's README: Code: NOTE that in -b "breadth-first" mode, GMP-ECM reads all candidate numbers in the input stream and keeps them in memory, so if there are many large numbers to be tested, the memory requirement will increase noticeably.
 2011-01-24, 13:48 #6 akruppa     "Nancy" Aug 2002 Alexandria 25×7×11 Posts Not remotely. Breadth-first mode reads all input numbers into memory, then does one curve on each number in turn, up to the desired number of curves. May have a use if you want any one factor from a set of input numbers, but I don't seen much use beyond that. Most of its functionality could be replicated by a shell script that executes GMP-ECM repeatedly, doing one curve per input number per execution.
2011-01-24, 14:16   #7
R.D. Silverman

Nov 2003

26×113 Posts

Quote:
 Originally Posted by akruppa Not remotely. Breadth-first mode reads all input numbers into memory, then does one curve on each number in turn, up to the desired number of curves. May have a use if you want any one factor from a set of input numbers, but I don't seen much use beyond that. Most of its functionality could be replicated by a shell script that executes GMP-ECM repeatedly, doing one curve per input number per execution.
Ah. Thanks for the clarification.

I agree that this feature does not seem all that useful.

 2011-01-24, 15:20 #8 axn     Jun 2003 112508 Posts I've used it for brilliant number search.
 2011-01-24, 15:40 #9 bsquared     "Ben" Feb 2007 13×257 Posts I've never used it, but why remove functionality if it works?
 2011-01-24, 17:06 #10 akruppa     "Nancy" Aug 2002 Alexandria 25·7·11 Posts The main function is a mess of loops and gotos, I can't get it through my head. Every time I tried I was overcome by the thought "why can't I just bin this?"
 2011-01-24, 17:55 #11 chris2be8     Sep 2009 3·647 Posts I've used it to avoid having both tasks on a dual core machine running stage 1 and stage 2 at the same time. By running 1 task depth first and 1 breadth first I can get them to process the numbers in a different order. But I'm not sure if it gives any real speedup, even when the two tasks are on 1 CPU with hyperthreading. Chris K

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