Module: Geo::Distance

Defined in:
lib/mealib/geo/distance.rb

Class Method Summary collapse

Class Method Details

.calc(loc1, loc2) ⇒ Object 



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# File 'lib/mealib/geo/distance.rb', line 5

def calc(loc1, loc2)
  rad_per_deg = Math::PI / 180                                                                                      # PI / 180
  rkm         = 6371                                                                                                # Earth radius in kilometers
  rm          = rkm * 1000                                                                                          # Radius in meters

  dlat_rad    = (loc2[0] - loc1[0]) * rad_per_deg                                                                   # Delta, converted to rad
  dlon_rad    = (loc2[1] - loc1[1]) * rad_per_deg

  lat1_rad, lon1_rad = loc1.map { |i| i * rad_per_deg }
  lat2_rad, lon2_rad = loc2.map { |i| i * rad_per_deg }

  a = Math.sin(dlat_rad / 2) ** 2 + Math.cos(lat1_rad) * Math.cos(lat2_rad) * Math.sin(dlon_rad / 2) ** 2
  c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a))

  rm * c                                                                                                            # Delta in meters
end