Native HyperLogLog for node.js

See http://en.wikipedia.org/wiki/HyperLogLog.

Based on https://github.com/avz/hll.

Example

var HLL = require('hll-native').HLL;

var tries = 5;

for(var n = 0; n < tries; n++) {
    var start = Date.now();
    var o = {};

    var obj = new HLL(20);

    for(var i = 0; i < 10000000; i++) {
        obj.add('hello_' + i);
    }

    console.log(
        '[' + (n + 1) + ' / ' + tries + ']',
        'Approximated set size:', obj.count() + '.',
        'Elapsed time:', Date.now() - start, 'ms'
    );
}

[1 / 5] Approximated set size: 10000341. Elapsed time: 2142 ms
[2 / 5] Approximated set size: 10000341. Elapsed time: 2133 ms
[3 / 5] Approximated set size: 10000341. Elapsed time: 2142 ms
[4 / 5] Approximated set size: 10000341. Elapsed time: 2121 ms
[5 / 5] Approximated set size: 10000341. Elapsed time: 2118 ms

Memory usage and error values

bits	size (bytes)	standard error
4	16	26.00%
5	32	18.38%
6	64	13.00%
7	128	9.19%
8	256	6.50%
9	512	4.60%
10	1024	3.25%
11	2048	2.30%
12	4096	1.62%
13	8192	1.15%
14	16384	0.81%
15	32768	0.57%
16	65536	0.41%
17	131072	0.29%
18	262144	0.20%
19	524288	0.14%
20	1048576	0.10%

Prototype

/**
 * Create new HyperLogLog storage with specified size and standard error.
 *
 * Memory usage for storage calculated as (1 << bits) bytes.
 * Standard error described in table above
 *
 * @param {number} bits
 */
var HLL = function(bits) {};

/**
 * Add key to storage
 * @param {string} key
 */
HLL.prototype.add = function(key) {};

/**
 * Get approximated set size with selected standard error
 * @returns {number}
 */
HLL.prototype.count = function() {};