geo_swap.rb in geo_swap-0.0.2

- old
+ new
@@ -1,5 +1,74 @@
 require "geo_swap/version"
+require 'geo_swap/zone'
+require 'geo_swap/utilities'
 
 module GeoSwap
-  # Your code goes here...
+  extend Utilities
+
+  def lat_long_to_utm(lat, long)
+    validate_range(lat, long)
+    lat_radians = degrees_to_radians(lat)
+    long_radians = degrees_to_radians(long)
+
+    zone = Zone.new(long)
+    origin_radians = degrees_to_radians(zone.origin)
+
+    equator_factor = (EQUATORIAL_RADIUS / Math.sqrt(1 - (ECC_SQUARED * (Math.sin(lat_radians) ** 2)))
+    squared_lat_tangent = Math.tan(lat_radians) ** 2
+    ecc_prime_factor = ECC_PRIME_SQUARED * (Math.cos(lat_radians) ** 2)
+    origin_factor = Math.cos(lat_radians) * (long_radians - origin_radians)
+
+
+    ecc_1 = (1 - ecc(1, 1, 4) - ecc(2, 3, 64) - ecc(3, 5, 256))
+    ecc_2 = ecc(1, 3, 8) + ecc(2, 3, 32) + ecc(3, 45, 1024)
+    ecc_3 = ecc(2, 15, 256) + ecc(3, 45, 1024)
+    ecc_4 = ecc(3, 35, 3072)
+
+    latRad_1 = lat_radians
+    latRad_2 = Math.sin(2 * lat_radians)
+    latRad_3 = Math.sin(4 * lat_radians)
+    latRad_4 = Math.sin(6 * lat_radians)
+
+    northing_factor = EQUATORIAL_RADIUS * (
+      ecc_1 * latRad_1 -
+      ecc_2 * latRad_2 +
+      ecc_3 * latRad_3 -
+      ecc_4 * latRad_4
+    )
+
+  end
+
+  module_function :lat_long_to_utm
+
+
+  private
+
+  MAX_LATITUDE = 90.0
+  MIN_LATITUDE = -90.0
+  MAX_LONGITUDE = 180
+  MIN_LONGITUDE = -180
+  MAX_CONVERSION_LATITUDE = 84.0
+  MIN_CONVERSION_LATITUDE = -80.0
+
+  EQUATORIAL_RADIUS = 6378137.0
+  ECC_SQUARED = 0.006694380023
+  ECC_PRIME_SQUARED = ECC_SQUARED / (1 - ECC_SQUARED)
+
+  def self.validate_range(lat, long)
+    unless lat.between?(MIN_LATITUDE, MAX_LATITUDE) && long.between?(MIN_LONGITUDE, MAX_LONGITUDE)
+      raise InputError, 'Input coordinates are invalid'
+    end
+
+    unless lat.between?(MIN_CONVERSION_LATITUDE, MAX_CONVERSION_LATITUDE)
+      raise InputError, 'Conversions are unreliable close to the polar regions'
+    end
+  end
+
+  def self.ecc(power, numerator, denominator)
+    ecc = ECC_SQUARED ** power
+    (numerator * ecc) / denominator
+  end
+
 end
+
+class GeoSwap::InputError < StandardError; end