haversine.pfx

// Function to calculate the distance between two geographic coordinates
GetDistance(lat1:Number, lon1:Number, lat2:Number, lon2:Number):Number = With(
    {
        // Convert latitude and longitude differences from degrees to radians


        dLat: (lat2 - lat1) * Pi() / 180.0,
        dLon: (lon2 - lon1) * Pi() / 180.0,
        // Convert original latitudes to radians


        rLat1: lat1 * Pi() / 180.0,
        rLat2: lat2 * Pi() / 180.0
    },
    With(
        {
            // Apply the Haversine formula


            a: (Power(
                Sin(dLat / 2),
                2
            ) + Power(
                Sin(dLon / 2),
                2
            ) * Cos(rLat1) * Cos(rLat2)),
            // Earth's radius in kilometers


            rad: 6371,
            convert_to_miles: 0.621371
        },
        // Final distance calculation using the inverse haversine and convert to miles


        (rad * (2 * Asin(Sqrt(a)))) * convert_to_miles
    )
);