module Geocoder::Calculations

def earth_radius(units = nil)

Use Geocoder.configure(:units => ...) to configure default units.
Radius of the Earth in the given units (:mi or :km).
#

def earth_radius(units = nil)
  units ||= Geocoder.config.units
  case units
    when :km; EARTH_RADIUS
    when :mi; to_miles(EARTH_RADIUS)
    when :nm; to_nautical_miles(EARTH_RADIUS)
  end
end