Accord.Statistics.Distributions.Univariate.HyperbolicSecantDistribution.DistributionFunction C# (CSharp) Method

        public override double DistributionFunction(double x)
        {
            double angle = Math.Atan(Math.Exp(x * Math.PI / 2.0));
            return 2 * angle / Math.PI;
        }

        public void ConstructorTest1()
        {
            var sech = new HyperbolicSecantDistribution();

            double mean = sech.Mean;     // 0.0
            double median = sech.Median; // 0.0
            double mode = sech.Mode;     // 0.0
            double var = sech.Variance;  // 1.0

            double cdf = sech.DistributionFunction(x: 1.4); // 2.2939067361538474
            double pdf = sech.ProbabilityDensityFunction(x: 1.4); // 0.10955386512899701
            double lpdf = sech.LogProbabilityDensityFunction(x: 1.4); // -2.2113389316917877

            double ccdf = sech.ComplementaryDistributionFunction(x: 1.4); // -1.2939067361538474
            double icdf = sech.InverseDistributionFunction(p: cdf); // 1.4000000017042402

            double hf = sech.HazardFunction(x: 1.4); // -0.084669058493850285

            string str = sech.ToString(); // Sech(x)

            Assert.AreEqual(0, mean);
            Assert.AreEqual(0, median);
            Assert.AreEqual(1, var);
            Assert.AreEqual(0, mode);
            Assert.AreEqual(2.2939067361538474, cdf);
            Assert.AreEqual(0.10955386512899701, pdf);
            Assert.AreEqual(-2.2113389316917877, lpdf);
            Assert.AreEqual(-0.084669058493850285, hf);
            Assert.AreEqual(-1.2939067361538474, ccdf);
            Assert.AreEqual(1.4000000017042402, icdf, 1e-13);
            Assert.AreEqual("Sech(x)", str);

            Assert.IsFalse(double.IsNaN(icdf));
        }