Accord.Statistics.Distributions.Univariate.MannWhitneyDistribution.MannWhitneyDistribution C# (CSharp) Method

        public MannWhitneyDistribution(double[] ranks, 
            [PositiveInteger] int n1, [PositiveInteger] int n2)
        {
            this.Ranks = ranks;
            this.Samples1 = n1;
            this.Samples2 = n2;
            int nt = n1 + n2;

            if (n1 <= 0)
            {
                throw new ArgumentOutOfRangeException("n1",
                    "The first number of samples must be positive.");
            }

            if (n2 <= 0)
            {
                throw new ArgumentOutOfRangeException("n2",
                    "The second number of samples must be positive.");
            }

            this.smallSample = (n1 <= 30 && n2 <= 30);

            if (smallSample)
            {
                // For a small sample (< 30) the distribution is exact.

                int nc = (int)Special.Binomial(nt, n1);
                table = new double[nc];

                int i = 0; // Consider all possible combinations of samples
                foreach (double[] combination in Combinatorics.Combinations(Ranks, n1))
                    table[i++] = USample1(combination, Samples2);

                Array.Sort(table);
            }
        }