[Ecm-dev] ecm v6.0.1: library enhancement

Paul Zimmermann Paul.Zimmermann at loria.fr
Dim 9 Avr 21:49:55 CEST 2006

       Dear Thomas,

I forward your suggestion to all GMP-ECM developers.


> Date: Sun, 09 Apr 2006 14:20:16 +0200
> From: ThMO <thmo-13 at gmx.de>
> Hello Paul,
> I would like to make a suggestion in order to enhance the ECM library
> for a function, which is able to determine the expected running time
> for a given number to factor related to the given B1 parameter, like
> your ecm program does already.
> Since I'm using my "general-purpose" factorization routines using
> your ecm_factor() as the "working horse", in order to compute home-primes,
> it would be a great benefit IMHO, if there would be a function present,
> maybe realized as a 1st step for the stage-2 factorization of ecm_factor(),
> which would return the estimated time needed, in order to find a factor
> with the given B1 parameter.
> If it could be realized as the 1st step of ecm_factor(), setting up the
> parameters in the supplied parameter structure, another call to this
> function could continue exactly, where the 1st call finished with e.g.
> ECM_ECM_ESTIMATE_TIME, ECM_ECM_CONTINUE and analogous definitions for
> ECM_PM1 and ECM_PP1...
> The problem is, if a specific composite needs to be factored, this could
> be done using your ecm program directly and wait for the given timings.
> But this can't be done, if the program is running continously with ever
> increasing numbers generated, so to be able to abort execution, if the
> the processor the program is running on, will not find some factor in a
> "reasonable" time...
> This structure could look like:
>   struct estimated_time {
>       unsigned int  years, days, seconds;
>     };
> So if ( est.years > 0 || est.days >= 90) could abort execution in an early
> stage, where it doesn't makes sense to continue computation (on this CPU).
> What do you think about it?
> CU Tom.
> (Thomas M.Ott)
> Germany

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