public class MathHelper
    {
        public static decimal Dot3(decimal d)
        {
            return decimal.Parse(String.Format("{0:0.###}", d));
        }
 
        public static decimal Dot2(decimal d)
        {
            return decimal.Parse(String.Format("{0:0.##}", d));
        }
 
        public static decimal Dot4(decimal d)
        {
            return decimal.Parse(String.Format("{0:0.####}", d));
        }
 
        public static decimal Dot6(decimal d)
        {
            return decimal.Parse(String.Format("{0:0.######}", d));
        }
 
        /// <summary>
        /// 获取价格相差
        /// </summary>
        /// <param name="firstPrice">价格1</param>
        /// <param name="sencondPrice">价格2</param>
        /// <returns>价格差</returns>
        public static decimal GetDiffPrice(decimal firstPrice, decimal sencondPrice)
        {
            return firstPrice - sencondPrice;
        }
 
        /// <summary>
        /// 获取价格差百分比
        /// </summary>
        /// <param name="firstPrice">价格1</param>
        /// <param name="sencondPrice">价格2</param>
        /// <returns>价格差百分比</returns>
        public static decimal GetPercentDiffPrice(decimal firstPrice, decimal sencondPrice)
        {
            if (sencondPrice == 0)
                return 0;
            return MathHelper.Dot2((GetDiffPrice(firstPrice, sencondPrice) / sencondPrice) * 100);
        }
 
        /// <summary>
        /// 将小数值按指定的小数位数截位
        /// </summary>
        /// <param name="value">要截位的小数</param>
        /// <param name="length">小数位数，s大于等于0，小于等于28</param>
        /// <returns></returns>
        public static decimal ToFixed(decimal value, int length)
        {         
            decimal sp = Convert.ToDecimal(Math.Pow(10, length));
            return Math.Truncate(value) + Math.Floor((value - Math.Truncate(value)) * sp) / sp;
        }
 
        /// <summary>
        /// 将小数值按指定的小数位数进位(大于0进位)
        /// </summary>
        /// <param name="value">要进位的小数</param>
        /// <param name="length">小数位数，s大于等于0，小于等于28</param>
        /// <returns></returns>
        public static decimal ToCeiled(decimal value, int length)
        {
            decimal sp = Convert.ToDecimal(Math.Pow(10, length));
            return Math.Ceiling(value * sp) / sp;
        }
    }
//csharp/7022