Inheritance: UnivariateContinuousDistribution
        public void ConstructorTest1()
        {
            var log = new LogisticDistribution(location: 0.42, scale: 1.2);

            double mean = log.Mean;     // 0.42
            double median = log.Median; // 0.42
            double mode = log.Mode;     // 0.42
            double var = log.Variance;  // 4.737410112522892

            double cdf = log.DistributionFunction(x: 1.4); // 0.693528308197921
            double pdf = log.ProbabilityDensityFunction(x: 1.4); // 0.17712232827170876
            double lpdf = log.LogProbabilityDensityFunction(x: 1.4); // -1.7309146649427332

            double ccdf = log.ComplementaryDistributionFunction(x: 1.4); // 0.306471691802079
            double icdf = log.InverseDistributionFunction(p: cdf); // 1.3999999999999997

            double hf = log.HazardFunction(x: 1.4); // 0.57794025683160088
            double chf = log.CumulativeHazardFunction(x: 1.4); // 1.1826298874077226

            string str = log.ToString(CultureInfo.InvariantCulture); // Logistic(x; μ = 0.42, scale = 1.2)

            Assert.AreEqual(0.41999999999999998, mean);
            Assert.AreEqual(0.41999999999999998, median);
            Assert.AreEqual(4.737410112522892, var);
            Assert.AreEqual(1.1826298874077226, chf);
            Assert.AreEqual(0.693528308197921, cdf);
            Assert.AreEqual(0.17712232827170876, pdf);
            Assert.AreEqual(-1.7309146649427332, lpdf);
            Assert.AreEqual(0.57794025683160088, hf);
            Assert.AreEqual(0.306471691802079, ccdf);
            Assert.AreEqual(1.3999999999999997, icdf);
            Assert.AreEqual("Logistic(x; μ = 0.42, scale = 1.2)", str);
        }
        public void LogisticTest()
        {
            var target = new TukeyLambdaDistribution(lambda: 0);
            var logistic = new LogisticDistribution();

            compare(target, logistic, 1e-5);
        }
        public void EquivalencyTest3()
        {
            // when ksi -> 0, the shifted log-logistic reduces to the logistic distribution.

            double sigma = 0.42;  // scale
            double ksi = 0;  // shape
            double mu = 2.4;      // location

            var target = new ShiftedLogLogisticDistribution(location: mu, scale: sigma, shape: ksi);
            var log = new LogisticDistribution(mu, sigma);

            Assert.AreEqual(log.Mean, target.Mean);
            Assert.AreEqual(log.Median, target.Median);
            Assert.AreEqual(log.Mode, target.Mode);
            Assert.AreEqual(log.Variance, target.Variance);

            double actual, expected;

            for (double i = -10; i < 10; i += 0.1)
            {
                expected = log.DistributionFunction(i);
                actual = target.DistributionFunction(i);
                Assert.IsTrue(expected.IsRelativelyEqual(actual, 1e-15));

                expected = log.ProbabilityDensityFunction(i);
                actual = target.ProbabilityDensityFunction(i);
                Assert.IsTrue(expected.IsRelativelyEqual(actual, 1e-15));

                expected = log.LogProbabilityDensityFunction(i);
                actual = target.LogProbabilityDensityFunction(i);
                Assert.IsTrue(expected.IsRelativelyEqual(actual, 1e-10));

                expected = log.ComplementaryDistributionFunction(i);
                actual = target.ComplementaryDistributionFunction(i);
                Assert.IsTrue(expected.IsRelativelyEqual(actual, 1e-15));

                double p = log.DistributionFunction(i);
                expected = log.InverseDistributionFunction(p);
                actual = target.InverseDistributionFunction(p);
                Assert.AreEqual(expected, actual, 1e-5);

                expected = log.HazardFunction(i);
                actual = target.HazardFunction(i);
                Assert.IsTrue(expected.IsRelativelyEqual(actual, 1e-15));

                expected = log.CumulativeHazardFunction(i);
                actual = target.CumulativeHazardFunction(i);
                Assert.IsTrue(expected.IsRelativelyEqual(actual, 1e-15));
            }
        }