public void LogProbabilityFunctionTest()
        {
            IDistribution target = CreateMultivariateContinuousDistribution();

            double[] x        = { 0.4, 2 };
            double   expected = System.Math.Log(0.032309150392899);
            double   actual   = target.LogProbabilityFunction(x);

            Assert.AreEqual(expected, actual, 1e-10);
        }