test_gamma.cpp

// Description: Testing for the gamma function
// DocumentationOf: gamma.h

#include "test/test_init.h"

#include <pastel/sys/math/gamma.h>
#include <pastel/sys/math/factorial.h>
#include <pastel/sys/math/error.h>

namespace
{

    template <typename Real>
    void testInteger()
    {
        for (integer i = 1;i < 140;++i)
        {
            //std::cout << gamma<Real>(i) << " : " << std::exp(lnGamma<Real>(i)) << std::endl;
            REQUIRE(relativeError<Real>(gamma<Real>(i), std::exp(lnGamma<Real>(i))) < 9e-13);
        }

        // 20! < 2^64 - 1 < 21!
        for (integer i = 0; i < 140; ++i)
        {
            //std::cout << factorial<Real>(i) << " : " << gamma<Real>(i + 1) << std::endl;
            REQUIRE(relativeError<Real>(factorial<Real>(i),  gamma<Real>(i + 1)) < 5e-15);
        }
    }

}

TEST_CASE("integers (gamma)")
{
    testInteger<real64>();
}