十六進制的字符串轉換為double類型

      //將十六進制的字符串轉換為double類型
         public static double changeType(string sType)
         {
              double dType=0;
              for(int j=sType.Length,k=0;j>0;j--,k++)
              {
                  string sTemp1 = sType.Substring(j-1,1);
                  if(sTemp1=="A")
                  {
                       dType+=10*System.Math.Pow(16,k);
                  }
                  else if(sTemp1=="B")
                  {
                       dType+=11*System.Math.Pow(16,k);
                  }
                  else if(sTemp1=="C")
                  {
                       dType+=12*System.Math.Pow(16,k);
                  }
                  else if(sTemp1=="D")
                  {
                       dType+=13*System.Math.Pow(16,k);
                  }
                  else if(sTemp1=="E")
                  {
                       dType+=14*System.Math.Pow(16,k);
                  }
                  else if(sTemp1=="F")
                  {
                       dType+=15*System.Math.Pow(16,k);
                  }
                  else
                  {
                       dType += (int.Parse(sType.Substring(j-1,1)))*System.Math.Pow(16,k);
                  }
              }
              return dType;
         }