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Type:
Bug
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Resolution: Done
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Priority:
Major - P3
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None
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Affects Version/s: 3.0.6
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Component/s: Geo
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None
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ALL
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Repl F (01/29/16), Query 10 (02/22/16)
Result:
{
"dis" : 85.27473543648324,
"obj" : {
"_id" : ObjectId("567a6af8f2f0548bc9a9a4f2"),
"loc" : {
"type" : "Point",
"coordinates" : [
-24,
40
]
}
}
},
These are the distances using different formulas:
"n-vector" : 111.2,
"haversine" : 111.2,
"vincenty" : 110.77,
Problem:
https://github.com/mongodb/mongo/blob/master/src/mongo/db/geo/shapes.cpp
double spheredist_rad(const Point& p1, const Point& p2) {
Looking at https://en.wikipedia.org/wiki/N-vector the below is wrong
double cross_prod = (cosy1 * cosx1 * cosy2 * cosx2) + (cosy1 * sinx1 * cosy2 * sinx2) + (siny1 * siny2);
Shoulg be:
double cross_prod = (cosy1 * cosx1 * cosy2 * cosx2) + (cosx1 * siny1 * cosx2 * siny2) + (sinx1 * sinx2);
//Example https://ideone.com/8nhK37 #include <iostream> #include <math.h> using namespace std; struct Point { Point(); Point(double x, double y); std::string toString() const; double x; double y; }; Point::Point() : x(0), y(0) {} Point::Point(double x, double y) : x(x), y(y) {} double spheredist_rad(const Point& p1, const Point& p2) { double sinx1(sin(p1.x)), cosx1(cos(p1.x)); double siny1(sin(p1.y)), cosy1(cos(p1.y)); double sinx2(sin(p2.x)), cosx2(cos(p2.x)); double siny2(sin(p2.y)), cosy2(cos(p2.y)); double cross_prod = (cosy1 * cosx1 * cosy2 * cosx2) + (cosy1 * sinx1 * cosy2 * sinx2) + (siny1 * siny2); double cross_prod2 = (cosy1 * cosx1 * cosy2 * cosx2) + (cosx1 * siny1 * cosx2 * siny2) + (sinx1 * sinx2); cout << (acos(cross_prod) * 6378.1) << endl; cout << (acos(cross_prod2) * 6378.1)<< endl; } int main() { Point p1 = Point(-25 * M_PI / 180, 40 * M_PI / 180); Point p2 = Point(-24 * M_PI / 180, 40 * M_PI / 180); spheredist_rad(p1, p2); return 0; }