module(..., package.seeall)

PI = 3.14159265359
ERadius = 6371.393
function getDistance( lat1, lng1, lat2, lng2 )
    -- body
    local radLat1 = lat1 * (PI / 180)
    local radLat2 = lat2 * (PI / 180)

    local a = radLat1 - radLat2
    local b = (lng1 * (PI / 180)) - (lng2 * (PI / 180))
    
    local s = 2 * math.asin(math.sqrt(math.pow(math.sin(a/2),2) + math.cos(radLat1)*math.cos(radLat2)*math.pow(math.sin(b/2),2)))
    local s = s * ERadius
    local s = math.floor(s * 10000+0.5) / 10000
    return s
end