Hilbert conversions Returns Hilbert index of given cardinal point
function hilbertIndex(point, options) { // :: [Int, Int, ..] -> {} -> Int
    options = options || {}
    var index = 0, code,
        entry = options.entry || 0,
        direction = options.direction || 0,
        i = options.precision || bitwise.bitPrecision(Math.max.apply(null, point)) - 1,
        dim = point.length

    console.log(i)
    while (i >= 0) {

        var bits = 0
        var mask = 1 << dim - 1

        for (var k = 0; k < point.length; k++) {
            if (point[dim - (k+1)] & (1 << i)) {
                bits |= mask
            }
            mask >>>= 1
        }

        bits = grayTransform(entry, direction, bits, dim)
        code = grayInverse(bits)

        entry = entry ^ bitwise.rotateLeft(entrySequence(code), dim, 0, direction + 1)
        direction = (direction + directionSequence(code, dim) + 1) % dim
        index = (index << dim) | code

        i--
    }

    return index
}