[C#] 經緯度的轉換

private string coordinateTrans(string coordinate)
{
double pX = Convert.ToDouble(coordinate);//121.5422222;
double degX = Math.Floor(pX);//121
double arcMinX = Math.Floor((pX - degX) * 60);//32
double arcSecX = Math.Round((((pX - degX) * 60) - arcMinX) * 60);//32
string retStr = "";
retStr = degX.ToString() + "°" + arcMinX.ToString("00") + "'" + arcSecX.ToString("00") + "\"";
return retStr;
}