docs: private void columnOpTransform2(Matrix M, int low, int high, double x, int k, double y, boolean notlast, double z, double r, double q)
      {
          double p;
          for (int i = low; i <= high; i++)
          {
              p = x * M.get(i, k) + y * M.get(i, k+1);
              if (notlast)
              {
                  p = p + z * M.get(i, k+2);
                  M.set(i, k + 2,  M.get(i, k+2) - p * r);
              }
              M.increment(i, k,   -p);
              M.increment(i, k+1, -p*q);
          }
      }