Sparse Scheme Matrix Generator Code

        string PrintStructure(bool[,] s, out int nonZeroCount)
        {
            var output = new StringBuilder();
            int nzCount = 0;
            int n = (int) System.Math.Sqrt(s.Length);
            for (int i = 0; i < n; i++)
            {
                for (int j = 0; j < n; j++)
                {
                    if (s[i, j])
                    {
                        output.Append("(X)");
                        ++nzCount;
                    }
                    else
                        output.Append(" - ");
                }
                output.AppendLine();
            }

            int upperTriangularSize = s.Length * (s.Length - 1) / 2 + s.Length;
            output.AppendFormat("n: {2}, nz: {0} ({3} bytes), sparse: {1:F10}", nzCount, nzCount / (decimal) upperTriangularSize, n * n, nzCount * 4);

            nonZeroCount = nzCount;
            return output.ToString();
        }

        void FillRandom(int[] a, int max, Random rng)
        {
            for (int i = 0; i < a.Length; i++)
                a[i] = rng.Next(0, max);
        }

        void Shuffle(int[] a, Random rng)
        {
            for (int i = 0; i < a.Length; ++i)
            {
                var j = rng.Next(i, a.Length - 1);
                var tmp = a[i];
                a[i] = a[j];
                a[j] = tmp;
            }
        }


            var rng = new Random();
            var nodes = 50;
            var links = 100;
            var ind = new int[nodes];
            var isrc = new int[links];
            var idst = new int[links];
            var structure = new bool[nodes, nodes];

            for (int i = 0; i < nodes; i++)
                ind[i] = i;

            FillRandom(isrc, nodes, rng);
            FillRandom(idst, nodes, rng);

            int nzCountMin = int.MaxValue;
            int nzCountMax = 0;
            int nzTries = 0;
            long nzCountSum = 0;
            double nzCountSqSum = 0;
            var log = new StringBuilder();
            int nzCount;

            for (int i = 0; i < 100; ++i)
            {
                Shuffle(ind, rng);
                var scheme = new SPAirScheme();
                scheme.Init(null);
                CreateScheme(scheme, ind, isrc, idst);
                scheme.SchemeMatrixStructure(structure);
                var schemeStructure = PrintStructure(structure, out nzCount);
                scheme.SolutionMatrixStructure(structure);
                var solutionStructure = PrintStructure(structure, out nzCount);

                nzCountMin = System.Math.Min(nzCount, nzCountMin);
                nzCountMax = System.Math.Max(nzCount, nzCountMax);
                nzCountSum += nzCount;
                nzCountSqSum += nzCount * nzCount;
                ++nzTries;

                if (nzCount < nzCountSum / (double) nzTries)
                {
                    log.Append(schemeStructure);
                    log.Append("\n\n");
                    log.Append(solutionStructure);
                    log.Append("\n\n");
                }
            }

            log.AppendFormat("NZ stats ({0} probes): min: {1}, max: {2}, avg: {3}, squared average: {4}",
                             nzTries,
                             nzCountMin,
                             nzCountMax,
                             nzCountSum / nzTries,
                             (int) System.Math.Sqrt(nzCountSqSum / nzTries));

            mainText.Text = log.ToString();