//pi está predefinido en Yabasic
deg2rad = pi / 180    // define grados a radianes 0.01745..
radioTierra = 6372.8  // radio de la tierra en km

sub Haversine(lat1, long1, lat2, long2 , radio)
    d_long = deg2rad * (long1 - long2)
    theta1 = deg2rad * lat1
    theta2 = deg2rad * lat2
    dx = cos(d_long) * cos(theta1) - cos(theta2)
    dy = sin(d_long) * cos(theta1)
    dz = sin(theta1) - sin(theta2)
    return asin(sqr(dx*dx + dy*dy + dz*dz) / 2) * radio * 2
end sub

print " Distancia de Haversine entre BNA y LAX = ", Haversine(36.12, -86.67, 33.94, -118.4, radioTierra), " km"
end