Module: GeoCalc::Distance

Defined in:
lib/geo_calc/calc/distance.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.distance_to(base_point, point, precision = 4) ⇒ Numeric

Returns the distance from this point to the supplied point, in km (using Haversine formula)

from: Haversine formula - R. W. Sinnott, “Virtues of the Haversine”,

Sky and Telescope, vol 68, no 2, 1984

Parameters:

  • Latitude/longitude (GeoPoint) —

    of destination point

  • number (Numeric) —

    of significant digits to use for returned value

Returns:

  • (Numeric) —

    distance in km between this point and destination point



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# File 'lib/geo_calc/calc/distance.rb', line 23

def self.distance_to base_point, point, precision = 4
  # default 4 sig figs reflects typical 0.3% accuracy of spherical model
  precision ||= 4

  lat1 = base_point.lat.to_rad
  lon1 = base_point.lon.to_rad

  lat2 = point.lat.to_rad
  lon2 = point.lon.to_rad

  dlat = lat2 - lat1
  dlon = lon2 - lon1

  a = Math.sin(dlat/2) * Math.sin(dlat/2) + Math.cos(lat1) * Math.cos(lat2) * Math.sin(dlon/2) * Math.sin(dlon/2)
  c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a))
  d = base_point.earth_radius_km * c
  d.round(precision)
end

Instance Method Details

#distance_to(point, precision = 4) ⇒ Object 



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# File 'lib/geo_calc/calc/distance.rb', line 8

def distance_to point, precision = 4
  GeoCalc::Distance.distance_to self, point, precision
end