1/*
2 *  Mandelbrot example:
3 *
4 *    $ ./duk mandel.js
5 *    [...]
6 */
7
8function mandel() {
9    var w = 76, h = 28, iter = 100;
10    var i, j, k, c;
11    var x0, y0, xx, yy, xx2, yy2;
12    var line;
13
14    for (i = 0; i < h; i++) {
15        y0 = (i / h) * 2.5 - 1.25;
16
17        for (j = 0, line = []; j < w; j++) {
18            x0 = (j / w) * 3.0 - 2.0;
19
20            for (k = 0, xx = 0, yy = 0, c = '#'; k < iter; k++) {
21                /* z -> z^2 + c
22                 *   -> (xx+i*yy)^2 + (x0+i*y0)
23                 *   -> xx*xx+i*2*xx*yy-yy*yy + x0 + i*y0
24                 *   -> (xx*xx - yy*yy + x0) + i*(2*xx*yy + y0)
25                 */
26
27                xx2 = xx*xx; yy2 = yy*yy;
28
29                if (xx2 + yy2 < 4.0) {
30                    yy = 2*xx*yy + y0;
31                    xx = xx2 - yy2 + x0;
32                } else {
33                    /* xx^2 + yy^2 >= 4.0 */
34                    if (k < 3) { c = '.'; }
35                    else if (k < 5) { c = ','; }
36                    else if (k < 10) { c = '-'; }
37                    else { c = '='; }
38                    break;
39                }
40            }
41
42            line.push(c);
43        }
44
45        print(line.join(''));
46    }
47}
48
49try {
50    mandel();
51} catch (e) {
52    print(e.stack || e);
53}
54