CoffeeSript version of counting tile x y z or coordinates from tile x y z.

xyz tiles

long2tile = (lon, zoom) ->
    Math.floor (lon + 180) / 360 * Math.pow(2, zoom)

lat2tile = (lat, zoom) ->
    Math.floor (1 - Math.log(Math.tan(lat * Math.PI / 180) + 1 / Math.cos(lat * Math.PI / 180)) / Math.PI) / 2 * Math.pow(2, zoom)

tile2long = (x, z) ->
    x / Math.pow(2, z) * 360 - 180

tile2lat = (y, z) ->
    n = Math.PI - 2 * Math.PI * y / Math.pow(2, z)
    180 / Math.PI * Math.atan(0.5 * (Math.exp(n) - Math.exp(-n)))