Re: [Boost-users] [Random] Noob question: Random number generators inside function

On Tue, Apr 24, 2012 at 3:02 PM, Błażej Jaworowski wrote:

I have a Monte Carlo simulation program (Ising model) in which I wanted to use Boost.Random number generators instead of one from *Numerical Recipes. *It works when the generator is called only in main, but when I use it inside function, I have "identifier not found". I don't want to initialize them each time I call a function because this will repeat the sequences of random number. Is there a way to overcome it? I don't know much about typedefs and templates, so my initialization of the generator is just copied from some tutorial and changed in, I hope, appropriate places. Here is the example code (I wouldn't paste original program, it's too long, but here is the same problem)

// random_test.cpp : Defines the entry point for the console application. //

#include "stdafx.h" #include "iostream" #include <ctime> #include using namespace std; namespace boost { namespace random { template class lagged_fibonacci_engine; template class lagged_fibonacci_01_engine; typedef lagged_fibonacci_01_engine< double, 48, 607, 273 > lagged_fibonacci607; typedef lagged_fibonacci_01_engine< double, 48, 1279, 418 > lagged_fibonacci1279; typedef lagged_fibonacci_01_engine< double, 48, 2281, 1252 > lagged_fibonacci2281; typedef lagged_fibonacci_01_engine< double, 48, 3217, 576 > lagged_fibonacci3217; typedef lagged_fibonacci_01_engine< double, 48, 4423, 2098 > lagged_fibonacci4423; typedef lagged_fibonacci_01_engine< double, 48, 9689, 5502 > lagged_fibonacci9689; typedef lagged_fibonacci_01_engine< double, 48, 19937, 9842 > lagged_fibonacci19937; typedef lagged_fibonacci_01_engine< double, 48, 23209, 13470 > lagged_fibonacci23209; typedef lagged_fibonacci_01_engine< double, 48, 44497, 21034 > lagged_fibonacci44497; } }

void generate();

int _tmain(int argc, _TCHAR* argv[]) {const int rangeMin = 1; const int rangeMax = 10; typedef boost::uniform_real<> NumberDistribution; typedef boost::random::lagged_fibonacci9689 RandomNumberGenerator; typedef boost::variate_generator Generator; NumberDistribution distribution(rangeMin, rangeMax); RandomNumberGenerator generator; Generator numberGenerator(generator, distribution); generator.seed(time(0)); // seed with the current time generate(); return 0; } void generate(){cout << numberGenerator() << endl;}

Why don't you just pass a reference to your numberGenerator object to your generate() function? - Jeff