The following gives a quick idea of the capabilities of the library. Note that the classes are all defined in the RandomLib namespace.
#include "RandomLib/Random.hpp" unsigned u; unsigned long long l; float f; double d; long double e; bool b; RandomLib::Random r; std::cout << "Seed set to: " << r.SeedString() << std::endl; f = r.FixedU<float>(); // result in (0,1] with 24 bits of randomness d = r.Fixed(); // result in [0,1) with 53 bits of randomness e = r.FixedN<long double>(); // result in [0,1] with 64 bits of randomness d = r.FloatN(); // a random in [0,1] rounded to the nearest double u = r.Integer(); // a random unsigned in [0,2^32) l = r.Integer<unsigned long long>(); // a random unsigned long long u = r.Integer<16>(); // a random unsigned in [0,2^16) u = r.Integer(52U); // a random unsigned in [0,52) u = r(52); // the same, enables passing r to std::random_shuffle u = r.IntegerC(1,6); // a random integer in [1,6] b = r.Boolean(); // true with prob 1/2 b = r.Prob(4, 7); // true with prob 4/7 b = r.Prob(0.34); // true with prob 0.34 #include "RandomLib/NormalDistribution.hpp" RandomLib::NormalDistribution<> g; d = g(r); // sample from normal distribution #include "RandomLib/ExponentialDistribution.hpp" RandomLib::ExponentialDistribution<> x; d = x(r); // sample from exponential distribution
Here is a more fleshed out example. Compile, link, and run this with, for example
g++ -I.. -O2 -funroll-loops -o RandomExample RandomExample.cpp Random.cpp
./RandomExample
(Note that the -funroll-loops is important!) This example also compiles and runs under Windows with Visual C++.
/** * \file RandomExample.cpp * \brief Example of use of RandomSeed, MT19937, Random, etc. * * Compile/link with, e.g.,\n * g++ -I.. -O2 -funroll-loops -o RandomExample RandomExample.cpp Random.cpp\n * ./RandomExample * * Written by Charles Karney <charles@karney.com> and licensed under the LGPL. * For more information, see http://randomlib.sourceforge.net/ **********************************************************************/ #include <iostream> #include <vector> #include <string> #include <algorithm> #include "RandomLib/Random.hpp" #include "RandomLib/NormalDistribution.hpp" #include "RandomLib/RandomSelect.hpp" #define RANDOMEXAMPLE_CPP "$Id: RandomExample.cpp 6723 2010-01-11 14:20:10Z ckarney $" RCSID_DECL(RANDOMEXAMPLE_CPP) RCSID_DECL(NORMALDISTRIBUTION_HPP) RCSID_DECL(RANDOMSELECT_HPP) int main() { RandomLib::Random r; // r created with random seed std::cout << "Using " << r.Name() << "\n" << "with seed " << r.SeedString() << std::endl; { std::cout << "Estimate pi = "; size_t in = 0, num = 10000; for (size_t i = 0; i < num; ++i) { const double x = r.FixedS(); // r.FixedS() is in the interval (-1/2, 1/2) const double y = r.FixedS(); if (x * x + y * y < 0.25) ++in; // Inside the circle } std::cout << (4.0 * in) / num << std::endl; } { std::cout << "Tossing a coin 20 times: "; for (size_t i = 0; i < 20; ++i) std::cout << (r.Boolean() ? "H" : "T"); std::cout << std::endl; } { std::cout << "Throwing a pair of dice 15 times:"; for (size_t i = 0; i < 15; ++i) std::cout << " " << r.IntegerC(1,6) + r.IntegerC(1,6); std::cout << std::endl; } { // Weights for throwing a pair of dice unsigned w[] = { 0, 0, 1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1 }; // Initialize selection RandomLib::RandomSelect<unsigned> sel(w, w + sizeof(w)/sizeof(unsigned)); std::cout << "Another 20 throws:"; for (size_t i = 0; i < 20; ++i) std::cout << " " << sel(r); std::cout << std::endl; } { std::cout << "Draw balls from urn containing 5 red and 5 white balls: "; int t = 10, w = 5; while (t) std::cout << (r.Prob(w, t--) ? w--, "W" : "R"); std::cout << std::endl; } { std::cout << "Shuffling the digits 0..9: "; std::string digits = "0123456789"; std::random_shuffle(digits.begin(), digits.end(), r); std::cout << digits << std::endl; } { std::cout << "Estimate mean and variance of normal distribution: "; double m = 0; double s = 0; int k = 0; RandomLib::NormalDistribution<> n; while (k++ < 10000) { double x = n(r); double m1 = m + (x - m)/k; s += (x - m) * (x - m1); m = m1; } std::cout << m << ", " << s/(k - 1) << std::endl; } { typedef float real; enum { prec = 4 }; std::cout << "Some low precision reals (1/" << (1<<prec) << "): "; for (size_t i = 0; i < 5; ++i) std::cout << " " << r.Fixed<real, prec>(); std::cout << std::endl; } std::cout << "Used " << r.Count() << " random numbers" << std::endl; try { // This throws an error if there's a problem RandomLib::MRandomGenerator32::SelfTest(); std::cout << "Self test of " << RandomLib::MRandomGenerator32::Name() << " passed" << std::endl; RandomLib::MRandomGenerator64::SelfTest(); std::cout << "Self test of " << RandomLib::MRandomGenerator64::Name() << " passed" << std::endl; RandomLib::SRandomGenerator32::SelfTest(); std::cout << "Self test of " << RandomLib::SRandomGenerator32::Name() << " passed" << std::endl; RandomLib::SRandomGenerator64::SelfTest(); std::cout << "Self test of " << RandomLib::SRandomGenerator64::Name() << " passed" << std::endl; } catch (std::out_of_range& e) { std::cerr << "Self test FAILED: " << e.what() << std::endl; return 1; } return 0; }
Typical output from this program is:
Using RandomEngine<SFMT19937<Random_u32>,MixerSFMT> with seed [360536,1209342001,31919,562196172,2008] Estimate pi = 3.1384 Tossing a coin 20 times: HTHTTHHHHHHHHTTHTTTH Throwing a pair of dice 15 times: 8 5 2 11 5 10 8 3 5 2 9 6 11 7 12 Another 20 throws: 7 7 8 8 9 10 8 9 10 11 9 4 5 4 9 4 11 6 5 8 Draw balls from urn containing 5 red and 5 white balls: RWWWWRRWRR Shuffling the digits 0..9: 3804916527 Estimate mean and variance of normal distribution: 0.00602807, 0.975485 Some low precision reals (1/16): 0.1875 0.75 0.4375 0.4375 0.9375 Used 94943 random numbers Self test of RandomEngine<MT19937<Random_u32>,MixerSFMT> passed Self test of RandomEngine<MT19937<Random_u64>,MixerSFMT> passed Self test of RandomEngine<SFMT19937<Random_u32>,MixerSFMT> passed Self test of RandomEngine<SFMT19937<Random_u64>,MixerSFMT> passed
1.7.5