Accord.Tests.Statistics.WilcoxonDistributionTest.CumulativeExactTest C# (CSharp) Method

        public void CumulativeExactTest()
        {
            // example from https://onlinecourses.science.psu.edu/stat414/node/319

            double[] ranks = 
            {
                22, 2, 13, 24, 16, 15, 25, 10, 9, 11, 5, 
                17, 12, 20, 14, 30, 8, 6, 26, 19, 29, 27, 3, 28,
                7, 21, 23, 1, 18, 4
            };

            WilcoxonDistribution target = new WilcoxonDistribution(ranks);

            Assert.AreEqual(232.5, target.Mean);
            Assert.AreEqual(2363.75, target.Variance);
            Assert.AreEqual(Math.Sqrt(2363.75), target.StandardDeviation);

            double actual = target.DistributionFunction(200);
            double expected = 0.2546;
            Assert.AreEqual(expected, actual, 1e-2);

            double inv = target.InverseDistributionFunction(actual);

            Assert.AreEqual(200, inv);
        }