code: public static double subtract(double minuend, double reduction) {
          BigDecimal minuendBd = new BigDecimal(Double.toString(minuend));
          BigDecimal reductionBd = new BigDecimal(Double.toString(reduction));
          return minuendBd.subtract(reductionBd).doubleValue();
      }
docs: 减法。
  
  @param minuend   被减数
  @param reduction 减数
  @return 计算结果