Calculate distance between two points directly in SQLite

Question

In my web/MySQL application I have something like this to get distance between two points:

6371 * acos(cos(radians(-19.83996)) * cos(radians(lat)) * cos(radi         


        

Answer 1

Insert cos_lat_rad,sin_lat_rad,cos_lon_rad,sin_lon_rad in to your table

contentValues.put("cos_lat_rad", Math.cos(deg2rad(latitude)));
contentValues.put("sin_lat_rad", Math.sin(deg2rad(latitude)));
contentValues.put("cos_lon_rad", Math.cos(deg2rad(longitude)));
contentValues.put("sin_lon_rad", Math.sin(deg2rad(longitude)));

degree to radian

public static double deg2rad(double deg) {
    return (deg * Math.PI / 180.0);
}

query , distance in km

 Cursor c=database.dis(String.valueOf(Math.cos((double) distance / (double) 6380)), Math.cos(deg2rad(latitude)), Math.sin(deg2rad(latitude)), Math.cos(deg2rad(longitude)), Math.sin(deg2rad(longitude)));

query

public Cursor dis(String dis, double cos_lat_rad, double sin_lat_rad, double cos_lon_rad, double sin_lon_rad) {

    Cursor cursor = sqLiteDatabase.rawQuery("SELECT * ,(" + sin_lat_rad + "*\"sin_lat_rad\"+" + cos_lat_rad + "*\"cos_lat_rad\"*(" + sin_lon_rad + "*\"sin_lon_rad\"+" + cos_lon_rad + "*\"cos_lon_rad\")) AS \"distance_acos\" FROM parish WHERE ("+sin_lat_rad+" * \"sin_lat_rad\" +"+ cos_lat_rad +"* \"cos_lat_rad\" * (+"+sin_lon_rad +"* \"sin_lon_rad\" + "+cos_lon_rad +"* \"cos_lon_rad\")) >"+dis+ " ORDER BY \"distance_acos\" DESC ", null);
    return cursor;

}

convert distance_acos to km

 if(c.moveToFirst())
        do {
            double distance_acos= c.getDouble(c.getColumnIndex("distance_acos"));
                     String Distance=String.valueOf(Math.acos(distance_acos) * 6380); 
        }while (c.moveToNext());