docs: private static void rowOpTransform(Matrix M, int low, int high, int n, double q, double p)
      {
          double z;
          for (int j = low; j <= high; j++)
          {
              z = M.get(n-1, j);
              M.set(n - 1, j,  q * z + p * M.get(n, j));
              M.set(n, j,      q * M.get(n, j) - p * z);
          }
      }