Index: lucene/contrib/spatial/src/java/org/apache/lucene/spatial/DistanceUtils.java
===================================================================
--- lucene/contrib/spatial/src/java/org/apache/lucene/spatial/DistanceUtils.java	(date 1321888557000)
+++ lucene/contrib/spatial/src/java/org/apache/lucene/spatial/DistanceUtils.java	(revision )
@@ -312,15 +312,15 @@
   }
 
   /**
-   * @param x1     The x coordinate of the first point, in radians
+   * Computes the haversine distance between two points. The arguments are in radians and provided in lat,lon order.
    * @param y1     The y coordinate of the first point, in radians
-   * @param x2     The x coordinate of the second point, in radians
+   * @param x1     The x coordinate of the first point, in radians
    * @param y2     The y coordinate of the second point, in radians
+   * @param x2     The x coordinate of the second point, in radians
    * @param radius The radius of the sphere
-   * @return The distance between the two points, as determined by the Haversine formula.
-
+   * @return The distance between the two points, as determined by the haversine formula.
    */
-  public static double haversine(double x1, double y1, double x2, double y2, double radius) {
+  public static double haversine(double y1, double x1, double y2, double x2, double radius) {
     double result = 0;
     //make sure they aren't all the same, as then we can just return 0
     if ((x1 != x2) || (y1 != y2)) {
@@ -328,8 +328,8 @@
       double diffY = y1 - y2;
       double hsinX = Math.sin(diffX * 0.5);
       double hsinY = Math.sin(diffY * 0.5);
-      double h = hsinX * hsinX +
-              (Math.cos(x1) * Math.cos(x2) * hsinY * hsinY);
+      double h = hsinY * hsinY +
+          (Math.cos(y1) * Math.cos(y2) * hsinX * hsinX);
       result = (radius * 2 * Math.atan2(Math.sqrt(h), Math.sqrt(1 - h)));
     }
     return result;
Index: solr/core/src/java/org/apache/solr/search/function/distance/HaversineFunction.java
===================================================================
--- solr/core/src/java/org/apache/solr/search/function/distance/HaversineFunction.java	(date 1321888557000)
+++ solr/core/src/java/org/apache/solr/search/function/distance/HaversineFunction.java	(revision )
@@ -75,22 +75,22 @@
     double[] p2D = new double[2];
     p1DV.doubleVal(doc, p1D);
     p2DV.doubleVal(doc, p2D);
-    double x1;
     double y1;
-    double x2;
+    double x1;
     double y2;
+    double x2;
     if (convertToRadians) {
-      x1 = p1D[0] * DistanceUtils.DEGREES_TO_RADIANS;
-      y1 = p1D[1] * DistanceUtils.DEGREES_TO_RADIANS;
-      x2 = p2D[0] * DistanceUtils.DEGREES_TO_RADIANS;
-      y2 = p2D[1] * DistanceUtils.DEGREES_TO_RADIANS;
+      y1 = p1D[0] * DistanceUtils.DEGREES_TO_RADIANS;
+      x1 = p1D[1] * DistanceUtils.DEGREES_TO_RADIANS;
+      y2 = p2D[0] * DistanceUtils.DEGREES_TO_RADIANS;
+      x2 = p2D[1] * DistanceUtils.DEGREES_TO_RADIANS;
     } else {
-      x1 = p1D[0];
-      y1 = p1D[1];
-      x2 = p2D[0];
-      y2 = p2D[1];
+      y1 = p1D[0];
+      x1 = p1D[1];
+      y2 = p2D[0];
+      x2 = p2D[1];
     }
-    return DistanceUtils.haversine(x1, y1, x2, y2, radius);
+    return DistanceUtils.haversine(y1, x1, y2, x2, radius);
   }