Calculates distance between two points using latitude and longitude in decimal degrees - IGOR Pro

haversine.ipf

// calculates spherical distance between two points on earth given coords in decimal degrees
// uses haversine formula
// radius of earth is taken to be 6371 km (IUGG/WGS-84 mean)
Function SphericalDistanceBetweenTwoPoints(lat1, long1, lat2, long2)
    Variable lat1, long1, lat2, long2
    
    // convert inputs in degrees to radians
    lat1*= pi/180
    long1*= pi/180
    lat2*= pi/180
    long2*= pi/180
    
    Variable dlon = long1 - long2
    Variable dlat = lat1 - lat2
    Variable aa = ((sin(dlat / 2) ^ 2) + cos(lat1) * cos(lat2) * (sin(dlon / 2) ^ 2))
    Variable cc = 2 * atan2(sqrt(aa), sqrt(1 - aa))
    Variable dd = 6371 * cc
    
    // return distance in metres
    return dd * 1000
end

// example usage with two 1D waves called lat and lon, distance between rows 0 and 1
Print DistanceBetweenTwoPoints(lon[0],lat[0],lon[1],lat[1])

Updated by cpr https://www.wavemetrics.com/comment/20517#comment-20517