[metslib] Problem with random_shuffle

[Mirko Maischberger]

Hello,

Thank you for debugging and for having tracked the error down.

I'm aware of some compatibility issues/bugs in the tr1/random libraries. I
will look into the problem in the next few days and I hope to release a fix
real soon.

Mirko


On Tue, Nov 9, 2010 at 1:01 AM, Shahin Gelareh <shahin.gelareh at gmail.com>wrote:

> Hi everybody,
>
> It seems like there have been a lot of changes from 4.3 to 5. Thanks for
> the efforts.
> The code I had in 4.3 does not work anymore with 5, it is of course
> migratable but now the main concern is regarding the suffleing algorithm of
> STL.
> The results in windows and using MSVC (MSVS2010)compiler is not what one
> expects. This is for example the case for qap example.
> I personally cannot run it. It reports exception and exits.
>
> One only needs to trace the code until:
>  template<typename random_generator>
>   void random_shuffle(permutation_problem& p, random_generator& rng)
>   {
> #if defined (METSLIB_HAVE_UNORDERED_MAP) && !defined
> (METSLIB_TR1_MIXED_NAMESPACE)
>     std::uniform_int<> unigen(0, p.pi_m.size());
>     std::variate_generator<random_generator,
>       std::uniform_int<> >gen(rng, unigen);
> #else
>     std::tr1::uniform_int<> unigen(0, p.pi_m.size());
>     std::tr1::variate_generator<random_generator,
>       std::tr1::uniform_int<> >gen(rng, unigen);
> #endif
>     std::random_shuffle(p.pi_m.begin(), p.pi_m.end(), gen);
>     p.update_cost();
>   }
>
>
> The output of this "std::random_shuffle(p.pi_m.begin(), p.pi_m.end(),
> gen);" is the original permutation where some of the cells are swapped BUT
> there are some strange numbers among the numbers. large positive values
> specifically. I searched a lot with no success about how to overcome.
>
> I was wondering if anyone has any idea?
>
>
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>



-- 
Mirko Maischberger
@ | mirko.maischberger at gmail.com
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