Distance calculator between 2 coordinates on a planet

SphericalDistance.scala

 /** Distance between 2 coordinates (in degrees) */
  def dist(
    p1: (Double, Double),             // Coordinate 1 (in degrees)
    p2: (Double, Double),             // Coordinate 2 (in degrees)
    manhattanDist: Boolean = false,   // If true, calculate Manhattan distance on the sphere :)
    diameter: Double =  7917.5        // Diameter of Earth in miles; set this to whatever planet/units you want
  ): Double = {
    import Math._
    
    def haversine(theta: Double) = (1 - cos(theta))/2
    
    def archaversine(delta: Double) = asin(sqrt(delta))
    
    val (lat1, long1) = p1
    val (lat2, long2) = p2
    val x1 = lat1.toRadians
    val y1 = long1.toRadians
    val x2 = lat2.toRadians
    val y2 = long2.toRadians
    val dx = x2 - x1
    val dy = y2 - y1
    val a = if (manhattanDist) {
      archaversine(haversine(dx)) + archaversine(haversine(dy))
    } else {
      archaversine(haversine(dx) + cos(x1)*cos(x2)*haversine(dy))
    }
    a*diameter
  }

/*********************************/
val ny = (40.7128, 74.0060)
val la = (34.0522, 118.2437)
  
println(dist(ny, la)) //Should be ~2446 miles between NYC and LA