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Changed haversine formula to be less sensitive to floating-point

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inexactness.
This commit is contained in:
DennisOSRM 2012-10-04 17:27:17 +02:00
parent c6dc476704
commit 0b2df9892d
2 changed files with 40 additions and 13 deletions
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51
DataStructures/Coordinate.h
View File

@ -57,18 +57,45 @@ inline double ApproximateDistance( const int lat1, const int lon1, const int lat
assert(lon1 != INT_MIN);
assert(lat2 != INT_MIN);
assert(lon2 != INT_MIN);
static const double DEG_TO_RAD = 0.017453292519943295769236907684886;
//Earth's quatratic mean radius for WGS-84
static const double EARTH_RADIUS_IN_METERS = 6372797.560856;
double latitudeArc = ( lat1/100000. - lat2/100000. ) * DEG_TO_RAD;
double longitudeArc = ( lon1/100000. - lon2/100000. ) * DEG_TO_RAD;
double latitudeH = sin( latitudeArc * 0.5 );
latitudeH *= latitudeH;
double lontitudeH = sin( longitudeArc * 0.5 );
lontitudeH *= lontitudeH;
double tmp = cos( lat1/100000. * DEG_TO_RAD ) * cos( lat2/100000. * DEG_TO_RAD );
double distanceArc = 2.0 * asin( sqrt( latitudeH + tmp * lontitudeH ) );
return EARTH_RADIUS_IN_METERS * distanceArc;
// static const double DEG_TO_RAD = 0.017453292519943295769236907684886;
// //Earth's quatratic mean radius for WGS-84
// static const double EARTH_RADIUS_IN_METERS = 6372797.560856;
// double latitudeArc = ( lat1/100000. - lat2/100000. ) * DEG_TO_RAD;
// double longitudeArc = ( lon1/100000. - lon2/100000. ) * DEG_TO_RAD;
// double latitudeH = sin( latitudeArc * 0.5 );
// latitudeH *= latitudeH;
// double lontitudeH = sin( longitudeArc * 0.5 );
// lontitudeH *= lontitudeH;
// double tmp = cos( lat1/100000. * DEG_TO_RAD ) * cos( lat2/100000. * DEG_TO_RAD );
// double distanceArc = 2.0 * asin( sqrt( latitudeH + tmp * lontitudeH ) );
// return EARTH_RADIUS_IN_METERS * distanceArc;
//double PI = 3.14159265358979323846;//4.0*atan(1.0);
double RAD = 0.017453292519943295769236907684886;
//std::cout << "RAD: " << RAD << std::endl;
//main code inside the class
double lt1 = lat1/100000.;
double ln1 = lon1/100000.;
double lt2 = lat2/100000.;
double ln2 = lon2/100000.;
double dlat1=lt1*(RAD);
double dlong1=ln1*(RAD);
double dlat2=lt2*(RAD);
double dlong2=ln2*(RAD);
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=6372797.560856;//I am doing miles, just change this to radius in kilometers to get distances in km
double distance=earth*cHarv;
return distance;
}
inline double ApproximateDistance(const _Coordinate &c1, const _Coordinate &c2) {

2
Descriptors/DescriptionFactory.h
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@ -51,7 +51,7 @@ public:
unsigned startName;
unsigned destName;
_RouteSummary() : lengthString("0"), durationString("0"), startName(0), destName(0) {}
void BuildDurationAndLengthStrings(double distance, unsigned time) {
void BuildDurationAndLengthStrings(const double distance, const unsigned time) {
//compute distance/duration for route summary
std::ostringstream s;
s << round(distance);