[Boost-users] Looking for a simple example of instantiating normal_distribution from the random library correctly

From: Kuntz, David A (david.a.kuntz_at_[hidden])
Date: 2004-08-03 17:04:44

> 		I am instantiating normal_distribution  from the random
> library incorrectly and looking for a simple example of how to do it
> correctly.
> 
> 		I compiled, built and ran random_test.cpp and can see
> when I step through the normal_distribution () operator that _r1 and
> _r2 have values < 1.
> 
> 		Here are the relevant excerpts from my incorrect attempt
> at instantiation and calling the () operator:
> 
> 		typedef boost::mt19937 base_generator_type;
> 
> 		boost::uint32_t x = 42u;
> 		Ideal4045EsmModel::base_generator_type
> base_generator(x);
> 
> 		double randomDrawResult;
> 		    
> 		boost::normal_distribution<double> boostNormalRand;
> 
> 		boostNormalRand.reset();
> 
> 		randomDrawResult = boostNormalRand(base_generator);  
> 
> 		This compiles, builds, and runs, but when I step through
> the normal_distribution () operator, _r1 and _r2 have very large
> positive values, resulting in  an attempt to take the log of a
> negative number and an Indefinite value being returned.
> 
> 		I am a relatively inexperienced C++ developer. I have
> built and stepped through random_test.cpp
> (http://www.boost.org/libs/random/random_test.cpp) and can see that
> its gets correct results, but I found it quite difficult to follow. Is
> there anyone out there who could show me a simpler way?
> 
> 		Thanks,
> 
> 		Dave
> 
> 
> 
>