Accord.Math.ReducedRowEchelonForm.ReducedRowEchelonForm C# (CSharp) Method

        public ReducedRowEchelonForm(double[,] value, bool inPlace = false)
        {
            if (value == null)
                throw new ArgumentNullException("value");

            rref = inPlace ? value : (double[,])value.Clone();

            int lead = 0;
            rows = rref.GetLength(0);
            cols = rref.GetLength(1);

            pivot = new int[rows];
            for (int i = 0; i < pivot.Length; i++)
                pivot[i] = i;


            for (int r = 0; r < rows; r++)
            {
                if (cols <= lead)
                    break;

                int i = r;

                while (rref[i, lead] == 0)
                {
                    i++;

                    if (i >= rows)
                    {
                        i = r;

                        if (lead < cols - 1)
                            lead++;
                        else break;
                    }
                }

                if (i != r)
                {
                    // Swap rows i and r
                    for (int j = 0; j < cols; j++)
                    {
                        var temp = rref[r, j];
                        rref[r, j] = rref[i, j];
                        rref[i, j] = temp;
                    }

                    // Update indices
                    {
                        var temp = pivot[r];
                        pivot[r] = pivot[i];
                        pivot[i] = temp;
                    }
                }

                // Set to reduced row echelon form
                var div = rref[r, lead];
                if (div != 0)
                {
                    for (int j = 0; j < cols; j++)
                        rref[r, j] /= div;
                }

                for (int j = 0; j < rows; j++)
                {
                    if (j != r)
                    {
                        var sub = rref[j, lead];
                        for (int k = 0; k < cols; k++)
                            rref[j, k] -= (sub * rref[r, k]);
                    }
                }

                lead++;
            }
        }