Quicker way to calculate geographic distance between two points

Question

I borrowed the following method from somewhere on the internet (Can\'t remember where). But its doing a straight forward process, finding the distance between two gps points

Answer 1

You might try the law of cosines for spherical trigonometry:

a = sin(lat1) * sin(lat2)
b = cos(lat1) * cos(lat2) * cos(lon2 - lon1)
c = arccos(a + b)
d = R * c

But it will be inaccurate for short distances (and probably just marginally faster).

There is a complete discussion here. However, the haversine formula is the most correct way, so aside from what others have suggested there may not be much you can do. @Alnitak's answer may work, but spherical to Cartesian conversions are not necessarily fast.