C++ - 纬度和经度距离计算器

Question

我的程序计算以千米为单位的两点之间的距离，给出两个纬度和经度值。

#include<iostream> 
#include <cmath> 

#define pi 3.14159265358979323846 

using namespace std; 

double calculateDistance(double lat1, double long1, double lat2, double long2) { 
    double dist; 
    dist = sin(lat1) * sin(lat2) + cos(lat1) * cos(lat2) * cos(long1 - long2); 
    dist = acos(dist); 
    dist = (6371 * pi * dist)/180; 
    return dist; 
} 

int main() { 
    cout << calculateDistance(51.752021, -1.257726, 51.507351, -0.127758); 
    return 0; 
} 

这就是我想实现的公式：

，我使用来测试我的输出，http://www.movable-type.co.uk/scripts/latlong.html，其中列明了答案应该是82.60公里计算器。 （我越来越33.6227公里）

Answer 1

像这样的东西应该工作（虽然没有测试）：

double toRad(double degree) { 
    return degree/180 * pi; 
} 

double calculateDistance(double lat1, double long1, double lat2, double long2) { 
    double dist; 
    dist = sin(toRad(lat1)) * sin(toRad(lat2)) + cos(toRad(lat1)) * cos(toRad(lat2)) * cos(toRad(long1 - long2)); 
    dist = acos(dist); 
//  dist = (6371 * pi * dist)/180; 
    //got dist in radian, no need to change back to degree and convert to rad again. 
    dist = 6371 * dist; 
    return dist; 
}