Re: [Boost-users] [random] getting a 50% probability generator

From: Jeffrey Holle (jeffreyholle_at_[hidden])
Date: 2007-10-05 15:00:51

Stupid mistake!
I was erroneously making the variate_generator a class attribute held by 
value.

I succeeded getting what I need by using a uniform_smallint<> six(1,100) 
and generating my sequence with (*pRand_gen)() % 2.

Thanks allot for the help.

Jeffrey Holle wrote:
> Brian Stadler wrote:
>> A few things,
>>
>> First, try this when creating your uniform_01 object,
>>
>> typedef boost::uniform_01<boost::mt19937> random_real;  <--you 
>> typedef'ed it here.
>> random_real actual_generator;
>> actual_generator() <----to output numbers between 0 and 1.
>>
>> Two,  don't use uniform_01.  The uniform_real class works much better 
>> and defaults to between 0 and 1.
>>
>>
>> Three,  it looks like you are wanting random ints 0 and 1, not random 
>> real numbers between 0 and 1.  For this have a look at the uniform_int 
>> or uniform_smallint class.  They are probably what you are looking for.
>>
>> Hope this helps.
>>
>> Brian
> Thanks for this information.
> It looks like I indeed need uniform_smallint, but I'm having trouble 
> with it.  This is what I'm trying to compile:
> 
>    std::tr1::mt19937 rng;
>    boost::uniform_smallint<int> six(1,6);
>    boost::variate_generator<std::tr1::mt19937&, 
> boost::uniform_smallint<int> > die(rng, six);
>    int x = die();
> 
> Note this from a boost webpage, with slight modifications.
> 
> The compiler error I'm getting is:
> 
> ../test.cpp:15: error: no matching function for call to 
> 'boost::variate_generator<std::tr1::mt19937&, 
> boost::uniform_smallint<int> >::variate_generator()'
> $BOOST_ROOT/boost/random/variate_generator.hpp:97: note: candidates are: 
> boost::variate_generator<Engine, 
> Distribution>::variate_generator(Engine, Distribution) [with Engine = 
> std::tr1::mt19937&, Distribution = boost::uniform_smallint<int>]
> 
> Can somebody point out what my problem is?