import kotlin.math.*
// ------------------------------------------------------------
// Convert degrees to radians
// ------------------------------------------------------------
fun degToRad(deg: Double): Double {
return deg * PI / 180.0
}
// ------------------------------------------------------------
// Compute the great-circle distance between two points on Earth
// using the Haversine formula.
// lat1, lon1, lat2, lon2 are in degrees.
// The result is returned in kilometers.
// ------------------------------------------------------------
fun haversine(lat1: Double, lon1: Double,
lat2: Double, lon2: Double): Double {
// Earth's mean radius in kilometers
val R: Double = 6371.0
// Convert all angles to radians
val rlat1: Double = degToRad(lat1)
val rlon1: Double = degToRad(lon1)
val rlat2: Double = degToRad(lat2)
val rlon2: Double = degToRad(lon2)
// Differences
val dlat: Double = rlat2 - rlat1
val dlon: Double = rlon2 - rlon1
// Haversine formula
// a is the Haversine of the central angle between the two points.
val a: Double =
sin(dlat / 2).pow(2) +
cos(rlat1) * cos(rlat2) *
sin(dlon / 2).pow(2)
// Central angle
// c is the central angle between the two points on the Earth’s surface.
val c: Double = 2 * asin(sqrt(a))
// Final distance
return R * c
}
fun main() {
// Example coordinates:
// Austin, Texas
val lat1: Double = 30.2672
val lon1: Double = -97.7431
// Houston, Texas
val lat2: Double = 29.7604
val lon2: Double = -95.3698
val distanceKm: Double = haversine(lat1, lon1, lat2, lon2)
// Convert kilometers to miles
val distanceMiles: Double = distanceKm * 0.621371
println("Distance: %.3f km".format(distanceKm))
println("Distance: %.3f miles".format(distanceMiles))
}
/*
run:
Distance: 235.352 km
Distance: 146.241 miles
*/
