A-M baby

Task/Haversine-formula/Go/haversine-formula.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+    "fmt"
+    "math"
+)
+
+func haversine(θ float64) float64 {
+    return .5 * (1 - math.Cos(θ))
+}
+
+type pos struct {
+    φ float64 // latitude, radians
+    ψ float64 // longitude, radians
+}
+
+func degPos(lat, lon float64) pos {
+    return pos{lat * math.Pi / 180, lon * math.Pi / 180}
+}
+
+const rEarth = 6372.8 // km
+
+func hsDist(p1, p2 pos) float64 {
+    return 2 * rEarth * math.Asin(math.Sqrt(haversine(p2.φ-p1.φ)+
+        math.Cos(p1.φ)*math.Cos(p2.φ)*haversine(p2.ψ-p1.ψ)))
+}
+
+func main() {
+    fmt.Println(hsDist(degPos(36.12, -86.67), degPos(33.94, -118.40)))
+}