Re: [Boost-users] boost::random: get same number sequences 32/64 bit?

Subject: Re: [Boost-users] boost::random: get same number sequences 32/64 bit?
From: Sebastian Mach (phresnel_at_[hidden])
Date: 2010-02-01 12:09:37

2010/2/1 Steven Watanabe <watanabesj_at_[hidden]>:
> AMDG
>
> Sebastian Mach wrote:
>>
>> This was indeed the problem. The one box had boost 1.35 installed, the
>> other one 1.41. Thanks for that hint.
>>
>>
>> I guess this is a) not the right place and b) the interest is probably
>> low (and let it be because it's not in the consciousness of many
>> people):
>>  * I realized that just replacing uniform_int.hpp with the older
>> version (that is, in a project local directory) and renaming
>> components was not easily possible
>>  * hence it might be hard in the future to trust boost::random in the
>> little corner where I really need portable random number sequences (as
>> users will literally work with seeds)
>>  * thus, I (and maybe some other persons) would love if, as with
>> spirit::classic, backwards compatibility could be provided somehow,
>> either via a typedef, a #define, or in the future with inline
>> namespaces
>>
>> Of course, if there is already a way that "guarantees" (not as in
>> law), I would be happy (after all, I am already happy to have a small
>> regression test generator which initially showed me the problem; if
>> there is interest, it is at
>> http://gitorious.org/picogen/picogen/trees/master/trunk/kallisto/test
>> :) ). Otherwise, I must really stick to hand written RNGs, which are
>> less portable in code, but more portable in sequences, as no RNG-lib I
>> know seems go have this kind of portability as a guideline.
>>
>
> You could try using boost::mt19937 directly without
> uniform_int.  The version of mt19937 in C++0x is
> guaranteed to produce a specific sequence (Required
> behavior: The 10000th consecutive invocation of a
> default-constructed object of type mt19937
> shall produce the value 4123659995.), and
> the Boost.Random version will be kept consistent
> with the standard.
>
> Also, boost::uniform_int should not change again unless
> there is a bug in it, and I'm about 99% certain that
> it is completely correct now.
>

Interesting, both the fact that mt19937 can be used directly
(I did not know that) and that C++0x will guarantee that sequence.

Thank you very much and Happy Programming