replace zxq.co/ripple/hanayo

vendor/github.com/pariz/gountries/math.go

@@ -0,0 +1,36 @@
+package gountries
+
+import "math"
+
+func Deg2Rad(deg float64) float64 {
+	return deg * math.Pi / 180
+}
+
+func CalculatePythagorasEquirectangular(lat1, lon1, lat2, lon2 float64) (d float64) {
+	lat1 = Deg2Rad(lat1)
+	lat2 = Deg2Rad(lat2)
+	lon1 = Deg2Rad(lon1)
+	lon2 = Deg2Rad(lon2)
+	var R = 6371.0 // km
+	var x = (lon2 - lon1) * math.Cos((lat1+lat2)/2)
+	var y = (lat2 - lat1)
+	d = math.Sqrt(x*x+y*y) * R
+
+	// Return Distance in Kilometers
+	return
+}
+
+func CalculateHaversine(lat1, lon1, lat2, lon2 float64) (d float64) {
+	var R = 6372.8 // Earth Radius in Kilometers
+
+	var dLat = Deg2Rad(lat2 - lat1)
+	var dLon = Deg2Rad(lon2 - lon1)
+	var a = math.Sin(dLat/2)*math.Sin(dLat/2) +
+		math.Cos(Deg2Rad(lat1))*math.Cos(Deg2Rad(lat2))*
+			math.Sin(dLon/2)*math.Sin(dLon/2)
+	var c = 2 * math.Atan2(math.Sqrt(a), math.Sqrt(1-a))
+	d = R * c
+
+	// Return Distance in Kilometers
+	return
+}