earth radius constants and simple test SERVER-1342

2 files changed, 19 insertions, 1 deletions

diff --git a/db/geo/2d.cpp b/db/geo/2d.cpp
index 84987e37c3c..51359d4dbfd 100644
--- a/db/geo/2d.cpp
+++ b/db/geo/2d.cpp
@@ -34,6 +34,10 @@
 
 namespace mongo {
 
+    double EARTH_RADIUS_KM = 6371;
+    double EARTH_RADIUS_MILES = EARTH_RADIUS_KM * 0.621371192;
+
+
     GeoBitSets geoBitSets;
 
     const string GEO2DNAME = "2d";
@@ -554,7 +558,7 @@ namespace mongo {
                 {
                     Point BNA (-1.5127, 0.6304);
                     Point LAX (-2.0665, 0.5924);
-
+                    
                     double dist1 = spheredist_rad(BNA, LAX);
                     double dist2 = spheredist_rad(LAX, BNA);
 
@@ -562,6 +566,14 @@ namespace mongo {
                     assert( 0.45305 <= dist1 && dist1 <= 0.45307 );
                     assert( 0.45305 <= dist2 && dist2 <= 0.45307 );
                 }
+                {
+                    Point JFK (-73.77694444, 40.63861111 );
+                    Point LAX (-118.40, 33.94);
+                    
+                    double dist = spheredist_deg(JFK, LAX) * EARTH_RADIUS_MILES;
+                    assert( dist > 2469 && dist < 2470 );
+                }
+
             }
         }
     } geoUnitTest;
diff --git a/db/geo/core.h b/db/geo/core.h
index edb5ea7f61b..dff174907a3 100644
--- a/db/geo/core.h
+++ b/db/geo/core.h
@@ -387,7 +387,12 @@ namespace mongo {
         double _y;
     };
 
+
+    extern double EARTH_RADIUS_KM;
+    extern double EARTH_RADIUS_MILES;
+
     // WARNING: _x and _y MUST be longitude and latitude in that order
+    // note: multiply by earth radius for distance
     inline double spheredist_rad( const Point& p1, const Point& p2 ) {
         // this uses the n-vector formula: http://en.wikipedia.org/wiki/N-vector
         // If you try to match the code to the formula, note that I inline the cross-product.
@@ -413,4 +418,5 @@ namespace mongo {
                     Point( p2._x * (M_PI/180), p2._y * (M_PI/180))
                );
     }
+
 }