Calculate distance between 2 GPS coordinates

Question

How do I calculate distance between two GPS coordinates (using latitude and longitude)?

Answer 1

you can find a implementation of this (with some good explanation) in F# on fssnip

here are the important parts:

let GreatCircleDistance<[<Measure>] 'u> (R : float<'u>) (p1 : Location) (p2 : Location) =
    let degToRad (x : float<deg>) = System.Math.PI * x / 180.0<deg/rad>

    let sq x = x * x
    // take the sin of the half and square the result
    let sinSqHf (a : float<rad>) = (System.Math.Sin >> sq) (a / 2.0<rad>)
    let cos (a : float<deg>) = System.Math.Cos (degToRad a / 1.0<rad>)

    let dLat = (p2.Latitude - p1.Latitude) |> degToRad
    let dLon = (p2.Longitude - p1.Longitude) |> degToRad

    let a = sinSqHf dLat + cos p1.Latitude * cos p2.Latitude * sinSqHf dLon
    let c = 2.0 * System.Math.Atan2(System.Math.Sqrt(a), System.Math.Sqrt(1.0-a))

    R * c