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