Diff: gps_utils.h

Revision:

2:3a288d8c816b

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gps_utils.h	Wed Mar 23 19:22:07 2016 +0000
@@ -0,0 +1,56 @@
+#ifndef __gps_utils_h__
+#define __gps_utils_h__
+
+#include <math.h>
+
+#ifndef M_PI
+    #define M_PI 3.14159265358979323846
+#endif
+
+#define TWO_PI (M_PI+M_PI)
+
+#define EARTH_RADIUS_METERS 6371000
+
+//Functions extracted from http://movable-type.co.uk/scripts/latlong.html
+
+//
+// Calculate the distance between two points on earth using the haversine function.
+// Most accurate and expensive distance calculating function in this library.
+// lat and lon values expected in radians.
+// Returns distance in meters
+//
+double haversine(double lat1, double lon1, double lat2, double lon2);
+
+//
+// Calculate the distance between two points on earth using the spherical law of cosines.
+// Less expencive than haversine, but not good at small distances.
+// lat and lon values expected in radians.
+// Returns distance in meters
+//
+double cosines(double lat1, double lon1, double lat2, double lon2);
+
+//
+// Calculate the distance between two points on earth using equirectangular approximation.
+// Least accurate and expensive distance calculating function, suitable only for small distances.
+// lat and lon values expected in radians.
+// Returns distance in meters
+//
+double equirectangular(double lat1, double lon1, double lat2, double lon2);
+
+//
+// Calculates the inital bearing a journey requires if traveling from lat1,lon1 to lat2,lon2.
+// (Bearing can naturally change as one travels along the sphere)
+// lat and lon values expected in radians.
+// Returns bearing in the range 0-2*PI
+//
+double startBearing(double lat1, double lon1, double lat2, double lon2);
+
+//
+// Calculates the bearing a journey will end on if traveling from lat1,lon1 to lat2,lon2.
+// (Bearing can naturally change as one travels along the sphere)
+// lat and lon values expected in radians.
+// Returns bearing in the range 0-2*PI
+//
+double endBearing(double lat1, double lon1, double lat2, double lon2);
+
+#endif //__gps_utils_h__
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