Ruby implementation of the haversine distance formula

ruby_haversine.rb

##
# Haversine Distance Calculation
#
# Accepts two coordinates in the form
# of a tuple. I.e.
#   geo_a  Array(Num, Num)
#   geo_b  Array(Num, Num)
#   miles  Boolean
#
# Returns the distance between these two
# points in either miles or kilometers
def haversine_distance(geo_a, geo_b, miles=false)
  # Get latitude and longitude
  lat1, lon1 = geo_a
  lat2, lon2 = geo_b

  # Calculate radial arcs for latitude and longitude
  dLat = (lat2 - lat1) * Math::PI / 180
  dLon = (lon2 - lon1) * Math::PI / 180


  a = Math.sin(dLat / 2) * 
      Math.sin(dLat / 2) +
      Math.cos(lat1 * Math::PI / 180) * 
      Math.cos(lat2 * Math::PI / 180) *
      Math.sin(dLon / 2) * Math.sin(dLon / 2)

  c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a))

  d = 6371 * c * (miles ? 1 / 1.6 : 1)
end

Thank you!