[gecode-users] How to set an arbitrary RandomGenerator for randomized branching?!?

[Javier Andrés Mena Zapata]

Hi,

Just curiosity... Do you prefer RNG speed, RNG space, general speed or
general space?

Cheers,

On Mon, May 18, 2009 at 2:55 AM, Mikael Zayenz Lagerkvist
<zayenz at gmail.com>wrote:

> Hi,
>
> Currently it is not possible to exchange the random number generator.
> Furthermore, the implementation uses properties of the random number
> generator that would most probably compromise efficiency if they were
> abstracted away (for example, the state is limited to a single
> unsigned int as seed). If you want to use your own random number
> generator, I would suggest writing your own subclasses of ViewSelBase
> and ValSelbase similar to ViewSelRnd and ValRnd.
>
> For curiosity, what is the reason that you want to change the random
> number generator used?
>
> Cheers,
> Mikael
>
> On Sat, May 16, 2009 at 12:37 AM, Martin Mann
> <mmann at informatik.uni-freiburg.de> wrote:
> >
> > Hi everybody,
> >
> > I digged a bit into the Gecode source about the randomized branching
> > supported since version 3.
> >
> > In line 124 in gecode/support/random.hpp I found the definition of
> > RandomGenerator internally used in the view selection:
> >
> >
> http://www.gecode.org/doc-latest/reference/group__FuncSupport.html#g02fe942f90a57a25639f09960dab4459
> >
> > As given there, it is just a typedef onto the
> > LinearCongruentialGenerator provided by Gecode but I would like to set
> > up my own random number generator...
> >
> > Is there a possibility to support user defined generators? e.g. in
> > coming versions?
> >
> > If not available right now, maybe you like the following suggestion:
> >
> > A possibility would be a super class 'RNG' that has to be implemented by
> > every generator plus a kind of factory class 'RNF' with static members
> only.
> > The RNF would be a wrapper around the current RNG instance to use
> > (stored in a static internal member). Thus, all Gecode internals that
> > need a random number use a static interface of RNF instead of some RNG
> > instance members. So the library gets independent of the concrete RNG
> > used and you get the possibility to register a user defined RNG within
> > the RNF. Per default the RNF can use the linear congruential generator
> > provided. The static interface and data member would avoid annoying
> > copies of RNGs all around and won't complicate your Gecode
> internals/source.
> >
> >
> > Just a suggestion... if it is already possible just ignore and please
> > let me know how to do with the current Gecode version. :)
> >
> >
> > Have a nice weekend,
> >
> > Martin
> >
> >
> > _______________________________________________
> > Gecode users mailing list
> > users at gecode.org
> > https://www.gecode.org/mailman/listinfo/gecode-users
> >
>
>
>
> --
> Mikael Zayenz Lagerkvist, http://www.ict.kth.se/~zayenz/<http://www.ict.kth.se/%7Ezayenz/>
>
> _______________________________________________
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> https://www.gecode.org/mailman/listinfo/gecode-users
>



-- 
"La buena educación, es lo que nos queda cuando se nos olvida todo lo que
nos han enseñado"
    ¿?

Javier Andrés Mena Zapata
http://StrategicDecision.net/
+57 (2) 318 1000 ext. 2910
Cali - Colombia
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