Calculate the distance between two points on the Earth's surface using a variety of algorithms.
The included algorithms are Vincenty, Haversine, Spherical Law of Cosines, Equirectangular distance, and polar co-ordinate flat-earth distance.
###Vincenty
- http://www.movable-type.co.uk/scripts/latlong-vincenty.html
- http://en.wikipedia.org/wiki/Vincenty's_formulae#Inverse_problem
###Haversine
###Spherical Law of Cosines
- http://www.movable-type.co.uk/scripts/latlong.html
- http://en.wikipedia.org/wiki/Spherical_law_of_cosines
###Equirectangular distance
- http://www.movable-type.co.uk/scripts/latlong.html
- http://en.wikipedia.org/wiki/Equirectangular_projection
###Polar co-ordinate flat-earth distance