Calculating distance between two coordinates

distanceFromLat: lat1 long: long1 toLat: lat2 long: long2
"Answer the distance in meters between two coordinates in float number representation."

| lat1Rad  lon1Rad lat2Rad lon2Rad earthRadius dLat dLon dLatSinSqrd dLonSinSqrd cosLatLat a c distance |
lat1Rad := lat1 degreesToRadians.
lon1Rad := long1  degreesToRadians.
lat2Rad := lat2 degreesToRadians.
lon2Rad := long2 degreesToRadians.
earthRadius := 6371.00.
dLat := lat2Rad - lat1Rad.
dLon := lon2Rad - lon1Rad.
dLatSinSqrd := (dLat / 2) sin squared.
dLonSinSqrd := (dLon / 2) sin squared.
cosLatLat := lat2Rad cos * lat1Rad cos.
a := dLatSinSqrd + (cosLatLat * dLonSinSqrd).
c := 2 * a sqrt arcSin.
distance := earthRadius * c.
^ distance