Added a test which checks the distance between London and Edinburgh is correctly calculated.

Author: manarth

tests/geospatial_haversine_london_edinburgh.phpt

@@ -0,0 +1,39 @@
+--TEST--
+Check the haversine function usage.
+--SKIPIF--
+<?php if (!extension_loaded("geospatial")) print "skip"; ?>
+--FILE--
+<?php 
+echo haversine(51.5171, 0.1062, 55.9500, 3.2200);
+/*
+	Test the haversine distance between London and Edinburgh.
+	
+	London:    51.5171° N, 0.1062° W (0.899143016 / 0.00185353967)
+	Edinburgh: 55.9500° N, 3.2200° W (0.976511716 / 0.0561996019)
+
+	Delta-lat:  4.4329° (0.0773687004)
+	Delta-long: 3.1138° (0.0543460622)
+
+  double a =  pow(sin(0.0773687004 * 0.5),2) + cos(0.899143016) * cos(0.976511716) * pow(sin(0.0543460622 * 0.5),2);
+  double a =  pow(sin(0.03868435),2)         +    cos(0.899143016) * cos(0.976511716) * pow(sin(0.027173031),2);
+  double a =  pow(0.03867470233,2)           +    0.62228103855    * 0.55991616262    * pow(0.02716968714,2);
+  double a =  0.0014957326                   +    0.62228103855    * 0.55991616262    * 0.00073819189
+  double a =  0.0014957326                   +    0.00025720466
+  double a =  0.00175293726
+  double c = 2.0 * atan2(sqrt(a), sqrt(1-a));
+  double c = 2.0 * atan2(sqrt(0.00175293726), sqrt(0.99824706274));
+  double c = 2.0 * 0.04188033525
+  double c = 0.08376067
+  return R * c;
+  return 
+
+	Accept defined (equatorial) Earth Radius in km (which is based on WGS-84):
+	- 6378137m (at the equator).
+
+	Sanity check - expected distance: approx 534km.
+*/
+?>
+--EXPECT--
+534.237028
+
+