PHP Geocoded point to point distance calculator comparison

Example USE:  http://hotchipsnsource.com/geocodetestsuite.php?lat1=11&lng1=14&lat2=81.000001&lng2=14&uom=K 
Point 1 Latitude ____|^^ |^^ |^^^^^^^^^ |^^ |^
Point 1 Longitude ____| | | |
Point 2 Latitude ____| | |
Point 2 Longitude ____| |
Units of Measure ____|

Try changing the 8 in lat2 to a 1
uom can be M,K,N or leave it off(only affects 1). Miles,Kilometers,Nautical Miles
Default set to K

RESULTS

1

Kinda basic, only one that accepts M & N at this time however.
7783.2704983896 K
microtime:0.00011897087097168
pro(fast & 9 lines of code),con(very inaccurate)

2

All rounder
7780.638149736 K
microtime:7.4863433837891E-5
pro(fast & small 23 lines of code),con(less accuracy then 3 but still quite naccurate)

3

Very very complex and accurate
However Some formula conditions are:
lat1>90 lon1>180 lat2>90 lon2>180
7780.3371647032 K
microtime:0.00013899803161621
pro(great accuracy),con(complex, processor taxing, 52 lines of code)