test_random.cpp

// Description: Testing for random variables
// Documentation: unit_testing.txt

#include "test/test_init.h"
#include <pastel/sys/random.h>
#include <vector>

namespace
{

    std::vector<real> sample(integer size)
    {
        std::vector<real> pmf(size, 0);

        integer n = 100 * size;
        for (integer i = 0;i < n;++i)
        {
            ++pmf[randomInteger(size)];
        }
        for (integer i = 0;i < size;++i)
        {
            pmf[i] /= n;
        }

        return pmf;
    }

}

TEST_CASE("RandomInteger (random)")
{
    auto test = [&](integer size)
    {
        std::vector<real> pmf = sample(size);

        for (integer i = 0;i < pmf.size();++i)
        {
            real correct = (real)1 / pmf.size();
            real error = absoluteError<real>(pmf[i], correct);
            if (error > 0.1)
            {
                /*
               std::cout << "error " << error << std::endl;
               for (real p : pmf)
               {
                   std::cout << p << " ";
               }
               std::cout << std::endl;
               */
                return false;
            }
        }
        return true;
    };

    {
        REQUIRE(test(1));
        REQUIRE(test(2));
        REQUIRE(test(3));
        REQUIRE(test(4));
        REQUIRE(test(5));
        REQUIRE(test(6));
        REQUIRE(test(7));
        REQUIRE(test(8));
        REQUIRE(test(9));
        REQUIRE(test(10));
        REQUIRE(test(11));
        REQUIRE(test(12));
        REQUIRE(test(13));
        REQUIRE(test(14));
        REQUIRE(test(15));
        REQUIRE(test(16));
    }
}