docs: public DoubleBinaryOperator determinant()
      {
          int sign = 1;
          SumBuilder sum = DoubleBinaryOperators.sumBuilder();
          PermutationMatrix pm = PermutationMatrix.getInstance(rows);
          int perms = pm.rows;
          for (int p=0;p<perms;p++)
          {
              MultiplyBuilder mul = DoubleBinaryOperators.multiplyBuilder();
              for (int i=0;i<rows;i++)
              {
                  mul.add(get(i, pm.get(p, i)));
              }
              sum.add(DoubleBinaryOperators.sign(sign, mul.build()));
              sign = -sign;
          }
          return sum.build();
      }