[英]calculating distance between two points in c#
i used this code which takes longitude and latitude of two different location and calculates the distance between them my code is 我使用此代码,它需要两个不同位置的经度和纬度,并计算它们之间的距离,我的代码是
protected void Button1_Click(object sender, EventArgs e)
{
double lat1= Convert.ToDouble(TextBox1.Text);
double lon1= Convert.ToDouble(TextBox2.Text);
double lat2= Convert.ToDouble(TextBox3.Text);
double lon2= Convert.ToDouble(TextBox4.Text);
var rlat1 = Math.PI * lat1/180;
var rlat2 = Math.PI * lat2/180;
var rlon1 = Math.PI * lon1/180;
var rlon2 = Math.PI * lon2 / 180;
var theta = lon1-lon2;
var rtheta = Math.PI * theta/180;
var dist = Math.Sign(rlat1) * Math.Sign(rlat2) + Math.Cos(rlat1) * Math.Cos(rlat2) * Math.Cos(rtheta);
dist = Math.Acos(dist);
dist = dist * 180/Math.PI;
dist = dist * 60 * 1.1515;
dist = dist * 1.609344 ;
TextBox5.Text = dist.ToString("0.######");
}
but for all the input values the result i am getting is NaN.please help me. 但是对于所有输入值,我得到的结果都是NaN。请帮助我。
Ok, because I led you up the garden path with my previous answer, I ported this to give you an algorithm that works: 好吧,因为我带领您与我以前的答案花园小径,我移植这个给你的作品的算法:
void Main()
{
double lat1=12.916933d,
lon1=77.562658d,
lat2=12.930140d,
lon2=77.587732d;
double dist = GetDistanceFromLatLonInKm(lat1, lon1, lat2, lon2);
// dist == 3.08890370651166 yay!
}
double GetDistanceFromLatLonInKm(double lat1,
double lon1,
double lat2,
double lon2) {
var R = 6371d; // Radius of the earth in km
var dLat = Deg2Rad(lat2 - lat1); // deg2rad below
var dLon = Deg2Rad(lon2 - lon1);
var a =
Math.Sin(dLat / 2d) * Math.Sin(dLat / 2d) +
Math.Cos(Deg2Rad(lat1)) * Math.Cos(Deg2Rad(lat2)) *
Math.Sin(dLon / 2d) * Math.Sin(dLon / 2d);
var c = 2d * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1d - a));
var d = R * c; // Distance in km
return d;
}
double Deg2Rad(double deg) {
return deg * (Math.PI / 180d);
}
Your calculation appears to work correctly when you supply fixed values:
当您提供固定值时,您的计算似乎正常工作:
var lat1 = 0d; var lon1 = 52d; var lat2 = 0d; var lon2 = -52d;
which rather implies that these conversions are failing:
而是暗示这些转换失败了:
double lat1 = Convert.ToDouble(TextBox1.Text); double lon1 = Convert.ToDouble(TextBox2.Text); double lat2 = Convert.ToDouble(TextBox3.Text); double lon2 = Convert.ToDouble(TextBox4.Text);
If you're still having trouble, place a breakpoint on these lines and take a look at the values of
TextBox1.Text
etc.
如果仍然遇到问题,请在这些行上放置一个断点,然后查看
TextBox1.Text
等的值。
For more predictable parsing of floating point numbers, it's best to supply culture information:
为了更可预测地解析浮点数,最好提供区域性信息:
Convert.ToDouble("1.2", System.Globalization.CultureInfo.InvariantCulture)
Check if decimal delimiter is valid. 检查小数分隔符是否有效。 It has to be comma or dot, depending on your regional settings. 它必须是逗号或点号,具体取决于您的区域设置。
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