使用 c++ 通过经纬度计算距离

Title:       Distance using Longitude and latitude
Author:      Chhibs 
Email:       annum0@gmail.com
Member ID:   12345
Language:    C++
Platform:    Windows, Linux
Technology:  WiMAX,WiFi, WDM
Level:       Intermediate, Advanced
Description: A quick code dump for haversine formula 
Section      Language c++
SubSection   Howto

引言

我在网站上看到过使用 C# 等计算距离的代码，使用的是海弗森公式，但没有使用 C++ 的，所以这里提供一段仅用于此的代码。

背景（可选）

我看到一些文章使用海弗森公式进行距离计算，但使用的是 .Net。由于我使用 C++ 编程（除非真的需要，否则不用 .Net），所以我将其移植到 C++，以下是代码。

来自数学论坛

http://mathforum.org/library/drmath/view/51879.html

Presuming a spherical Earth with radius R (see below), and that the
locations of the two points in spherical coordinates (longitude and
latitude) are lon1,lat1 and lon2,lat2, then the Haversine Formula 
(from R. W. Sinnott, "Virtues of the Haversine," Sky and Telescope, 
vol. 68, no. 2, 1984, p. 159): 

  dlon = lon2 - lon1
  dlat = lat2 - lat1
  a = (sin(dlat/2))^2 + cos(lat1) * cos(lat2) * (sin(dlon/2))^2
  c = 2 * atan2(sqrt(a), sqrt(1-a)) 
  d = R * c

will give mathematically and computationally exact results. The 
intermediate result c is the great circle distance in radians. The 
great circle distance d will be in the same units as R.

使用代码

我只是发布一段我用于一个类的代码片段，它为我计算距离。

// Sample format for latitide and longitudes
// double lat1=45.54243333333333,lat2=45.53722222,long1=-122.96045277777778,long2=-122.9630556;
// Below is the main code
        #include <cmath>
        double PI = 4.0*atan(1.0);
        
        //main code inside the class
        double dlat1=lat1*(PI/180);

        double dlong1=long1*(PI/180);
        double dlat2=lat2*(PI/180);
        double dlong2=long2*(PI/180);

        double dLong=dlong1-dlong2;
        double dLat=dlat1-dlat2;

        double aHarv= pow(sin(dLat/2.0),2.0)+cos(dlat1)*cos(dlat2)*pow(sin(dLong/2),2);
        double cHarv=2*atan2(sqrt(aHarv),sqrt(1.0-aHarv));
        //earth's radius from wikipedia varies between 6,356.750 km — 6,378.135 km (˜3,949.901 — 3,963.189 miles)
        //The IUGG value for the equatorial radius of the Earth is 6378.137 km (3963.19 mile)
        const double earth=3963.19;//I am doing miles, just change this to radius in kilometers to get distances in km
        double distance=earth*cHarv;