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Contents
# encoding: UTF-8
module Graticule
module Distance
#
# The Haversine Formula works better at small distances than the Spherical Law of Cosines
#
# Thanks to Chris Veness (http://www.movable-type.co.uk/scripts/LatLong.html)
# for distance formulas.
#
class Haversine < DistanceFormula
# Calculate the distance between two Locations using the Haversine formula
#
# Graticule::Distance::Haversine.distance(
# Graticule::Location.new(:latitude => 42.7654, :longitude => -86.1085),
# Graticule::Location.new(:latitude => 41.849838, :longitude => -87.648193)
# )
# #=> 101.061720831836
#
def self.distance(from, to, units = :miles)
from_longitude = from.longitude.to_radians
from_latitude = from.latitude.to_radians
to_longitude = to.longitude.to_radians
to_latitude = to.latitude.to_radians
latitude_delta = to_latitude - from_latitude
longitude_delta = to_longitude - from_longitude
a = sin(latitude_delta/2)**2 +
cos(from_latitude) *
cos(to_latitude) *
sin(longitude_delta/2)**2
c = 2 * atan2(sqrt(a), sqrt(1-a))
d = EARTH_RADIUS[units.to_sym] * c
end
end
end
end
Version data entries
9 entries across 9 versions & 1 rubygems